Please check the specific visa requirements for your country at the Hong Kong Immigration Department web site.
Generally, visas are not required for visitors from most countries. The length of allowed visa-free stay in Hong Kong varies from 14 days to 3 months. All visitors to Hong Kong must have a valid travel document, endorsed where necessary for Hong Kong. These should be valid for at least one month beyond your planned departure from Hong Kong, and in the case of certain nationalities, at least six months.