The solar sail takes advantages of solar radiation pressure to achieve orbital propulsion which offers a sustainable maneuvers method in deep space exploration. This paper proposes a coupled orbit -attitude control method which can control trajectory and attitude at the same time on solar sail. Firstly, by the torque and force generation a diffusion modulation of coupled orbit-attitude dynamical model has been given. Secondly, the distribution of sailboards on solar sail under the solar radiation pressure has been discussed. Thirdly, control laws based on the traditional state-dependent Riccati equation has been obtained to the coupled orbit-attitude problem. Then, numerical simulation of a solar sail on the Earth orbit which are based on the reflection modulation have been given.