Good place for a holiday as you can find some great inexpensive beach resorts if you do some research. Of course there are other attractions too, but I am not sure how much your other half knows about these things, or whether that is your primary motive for travel there. I have been there a few times surfing many years ago in Northern Luzon, an Island in Southern province of Mindanao. I also traveled to a lot to other places like Boracay, Moalboal in Cebu and Peurto Gallera on the Island of Mindoro. Like I said it was 10-15 years ago now that I visited and I did not care for the more seedy touristy bar type areas rather I prefered the small cottage on the beach, family run place. Big Cities Manila, Cebu were also not to my liking.
Anyway I digress, back to your question. If she has any idea of the female situation in the Phillos, you have no chance, even if your motives are purely travel related.

Tell her how it's breaking your heart, but some guy in his high and mighty office seems to be doing be best to make your life miserable. That you will have to leave China (not forever just a few days) as you work out some paperwork and go through all the fun the customs has in store for you. And how though you wish that you could spend the holiday with her, it's the only time you can get away from work long enough to make sure you get all the issues worked out. (Bonus if you can work up a tear or two).

Or just tell her that you're going and if she really loved you, she'd understand and be happy for you.

Business trip... Tell her you're going back home to visit family... if you're going to BS her say anything...

Tell her that you are attending a business related conference or something in Philippines. Promise her that you will behave and call her everynight. When you go back to China don't forget to buy her a Philippines gift Hire a graphic designer to make a brochure of this business related conference, then show it to her. A proof that she will let you go to this trip.and still love you

Explain to her how easy it is for a Filipino to say... i love you...... they so easy to pick up... Please im not trying to be funny.... but i spent a long time in Philippines and i can assure you its not worth it unless you really in love...
If you love your Chinese gf.... dont go...
Chinese NY means a lot to the Chinese if you invited to go to her family.

Dude, I've spent a lot of time there myself. If you get the okay call me!!! As much as I love looking at Chinese women the Filipinas leave them for dead when it comes to affection - unsolicited.
If you need an excuse and you like to scuba dive there is a place south of Cebu that is one of the best in the world. Seriously though, you got problems both getting away from your GF and surviving chaste in Phil. Keep your hand on your wallet tho.

Forget it. If you need to ask others to help you find an excuse then you're not good enough at telling lies and she won't believe you. She will then start asking questions which you won't be able to answer and you'll, probably, laugh when you try to sound convincing - don't ever laugh when you're telling lies, most women know this sign.

easy , tell her you need to visit a buddy from back home who just broke up with his wife, and he's feeling very depressed. go the whole nine on this one setup a dumby account and send emails back and forth. make the dude (no pun intended) 0seem a little suicidal , no matter how mean she is she cant object to that. but dont volunteer to show here the emails she might snoop and discover them herself

The truth. "I'm on this side of the planet and want to go to the Phillipines"

Yeah just tell her the truth. I'd prefer not to lie to my girlfriend and I would just tell her. If women have undue insecurity issues it's their fault and they will have to deal with it.

you shouldnt even lie to her! I believe she'll understand that

I am sure she will know you are going there to see another girl

If you manage to get to the Philipines make sure to go to Mindoro. The cleanest foreigner friendly place in the Philipines I have been. My personal recomendation is to go here  www.llbc.com.ph  , I have been there 3 times and done all my diving qualifications through them.  They have the raelly kind staff, the kind that will have beers with you after work, and the highest rated PADI dive resort in Mindoro. An epic time will definately be had!

I would tell her I am going to the Philippines for CNY. Grow a pair!

Exactly... Don't lie to her... Say that you are going exclusively for sex... She will never believe you. 

Tell her the truth. and if she don't allow you to go ask her why? she should have a valid reason why she don't want you to go there. keep in mind that big lies come from a small lie and its not really good in a relationship.

  Tell her that you need a Philipino vagina massage; it has been prescribed to you by your doctor, if you don't get it your pecker will fall off, but if you do get it it'll enhance your sexual performance no end. It is imperative that you look completely serious and a little worried when you say this, but that excuse works for me every time.

Well, almost every time. Ok, the last girl chopped off my pickle, but it stll works. Well, it kind of still works.

CAll me when you arrive here in philippines +639239270292 or we can chat on skype: alex_ng73 and my QQ is 1651692720 and my email is philippine.passport@yahoo.com