Based on difference in difference method and gravity equation, this paper analyzes the impact of CEPA on Hong Kong and its main trading partners' trade by using the data from 1998 to 2011. The research results show that CEPA promotes Hong Kong's import from provinces of mainland China higher by 35.1% to 87.0% than from other trading partners, but has no significant effect on boosting its export. The results match the background of Hong Kong's economic transformation and its role of international entrepot. Hong Kong's future development should rely on ...