Just submit the below documents to China embassy in Islambad, Pakistan in person or entrust someone else to do so:
1. your passport
2. one completed visa application form
3. one recent passport photo
4. copy of Chinese visa on the visa page of your passport
5. round-trip flight tickets and hotel reservation

if your application is accepted, you will be given a Pick-up Receipt, then go to the embassy on the date wrriten on the Receipt to pay for visa fee, pick up your visa and passport.