CEPA has been implemented for 10 years，promoting the development of service trade between Mainland and Hong Kong. However，big obstacle still remains. It needs an evaluation of service trade liberalization. Based on Hoekman Index，this paper measures the service trade liberalization between Hong Kong and the Mainland before and after the implementation of CEPA. The results show that the service trade liberalization between Hong Kong and the Mainland has improved to some extent both in breadth and in depth. But the implementation process of CEPA is relatively slow，and the promises coverage is not high in previous agreement. The opening on finance，communication and other sensitive sectors are still relatively conservative. Overall，as of the signing of CEPA 10，the service trade liberalization between Hong Kong and the Mainland is still low.