With the consumption of conventional energy，people will not adapt to the sustainable development of the society，the development and utilization of renewable resources such as solar energy has caused a common concerns. In order to improve the energy efficiency，using focusing type parabolic trough type collector，a solar energy automatic tracking system was designed. The mechanical structure of the automatic tracking device was described in detail. The experimental results show that the automatic tracking device meets the design requirements，it has the characters of lower consumption and lower cost.