hi im sandi from philippines but currently living in china.

Yes, you need to send her an invitation letter, as well as copies of your passport, residence permit and valid Chinese visa. Besides, proof of relationship is required, for you it should be your birth certificates. Hotel bookings are not necessary if she will stay in your place. The letter should include:
(1) Personal information of the applicant, such as name, gender,and date of birth.
(2) Purpose of the visit to China, travel itinerary such as date of entry and exit, places of visit, relationship between the inviter and the applicant, and who will bear the expenses of the applicant in China.