In order to optimize the video transmission in wireless network, a complete system is designed by combining dense small-cell network, software defined networking and scalable video coding technology. Through the cooperation between base stations in dense small-cell network, the radio spectrum utilization is improved, and the differential service is provided for different users by bitrate adaptation. This paper aims at maximizing the quality of user experience by making joint decision of user video layer selection and wireless resource allocation. By employing Lyapunov optimization method, the original problem is transformed into two independent subproblems that can be solved separately. A low complexity algorithm only relying on the current observation is presented. The experimental results verify that the proposed algorithm can perform well in dynamic environment and achieve a higher user experience.