To improve the efficiency of solar energy device for solar receiving, a new sun tracking device adopting parallel mechanism was put forward. The kinematics model was established by the position closedloop vector equation,the velocity Jacobian matrix was deduced, the agency’〖KG-*2〗s flexibility performance evaluation index was defined; the task working space of the sun tracking device was drawn,the relationship between the parameters was optimized by given constraint conditions in its task working space. It lays foundations for the device structure design.