A travel visa is needed for overseas visitors to mainland China. The visa should be obtained at the Chinese visa office in your home country before leaving.
Application can also be made from the visa office in Hong Kong for passport holders from most of the countries/regions, please allow 3 working days for normal visa, 2 working days for urgent visa, and 1 working day for very urgent visa. Some travel agents in Hong Kong provide service for Chinese visa application.
Make sure your passport is eligible to apply visa to China in Hong Kong; or obtain the visa before you leave for Hong Kong.