I am working in Shenzheng and now I want to go to Hongkong one day for meeting.

You need to apply for it. First, you need to provide copy of passport, the application form affixed with a passport-style photo, proof of your financial support, transportation and accommodation arrangement, and your travel plan as well as others. Next, submit the application to the liaison office of HK government in Shenzhen to apply for HK visit visa.