You can't visit Mainland China with the Hong Kong business visa, you have to apply for China tourist visa to go to Mainland China, Hong Kong, as the special administrative region, applies different exit & enter controls from Mainland China.

the requirements for China tourist visa applcation are:
(i) Original passport which has more than 6 months left before it expires from the date of application for a visa and sufficient blank visa pages.

(ii) One completed Visa Application Form with a recently-taken passport photo; all the items on the application form should be completed neatly with genuine information;

(iii) Proof of sufficient finances to cover all expenditures in China when requied. From 16th March 09 Applicant holding Indian Passport applying for first time Tourist Visa Require to submit Original Bank Certificate with minimum balance of Rs 1.5 lacs.

(iv) Confirmed return flight ticket and its photocopy.

(v) Covering letter from applicant's company or office.

(vi) Photocopy of personal data page of applicant's passport.
You'd better apply for China tourist visa in INDIA, maybe you can't get the China visa in Hong Kong

I will be going to china from HK in business visa
pls tell me how easy to get china business visa from HK