how can iapply visa to visit him

You may just apply for a China L family visit visa from the China embassy or consulate where your living place is under its consular jurisdiction. The required documents are:
1. Your passport with over 2 blank pages and at least 6 months validity left before expiration
2. A truly and completely filled application form affixed with one passport-size or 2x2
colored photo
3. Invitation letter from your husband in China and copies of his passport and Chinese residence permit
4. photocopy of the emergency contact information page in your passport
If it is your first time to China, you will also have to provide the followings:
1. Original NBI clearance valid for travel abroad
2. Your bank certificate with receipt or original passbook, or if your husband will sponsor the trip, provide his bank certificate
3. If you are employed, also provide company ID, SSS ID and contributions, TIN ID and latest ITR