Just apply for it from the Chinese embassy in Pakistan with the following documents:
(I) Original Visa Notice Sheet from an authorized governmental apparatus /organization inChina prescribing the visa validity, number of entries and stay period;
(II) Fully completed Visa Application Form in Chinese or English, attached with one of the applicant's recent color photograph (30mm X 40mm)
(III) Original passport with validity more than six months and minimum 2 blank visa pages;
(IV) Photocopy of the first 2 pages (personal information) of the passport and the recent Chinese visa page if there is any;
(V) Invitation letter from the company/organization/institution you want to visit inChina;
If this is your first visit to China, it is recommended that following documents are also prepared in case of necessity:
(VI) Your income certificate/up-to-date Personal Bank Statement
(VII) Your company's Registration Certificate (photocopy)
(VIII) A recommendation letter from your company/organization/ institution
(IX) A recommendation letter from Chamber of Commerce& Industry
(X) Your Tax Payment Receipt for last year (photocopy)
(XI) Your Character Certificate/Police Clearance Certificate