I am Pakistani, I want to apply for china for 1 years visa

Which type are you going to apply? Each kind has different requirements.

I don't know what type I am applying
For one year duration

Working with my friends there who are doings businesses their

You want to work in China, or just visit your friend, or visiting your friends while working?
If you just go there for visiting, it may be hard for you to apply a Tourist L. Passport holders of Pakistan cannot get a Tourist L as an individual.

If you want to work in China, you need to have a work permit and an invitation letter from a Chinese company. Then you can use them together with your valid passport, an application form with a recent taken photo and your medical report to apply in your local Chinese embassy.