For free space optical communication,due to the small diameter of the optical fi ber,the effective coupling of space light to optical fiber is very difficult.On the other hand,the optical signals should be converted into electrical signals.Then,the new idea of directly converting the spatial light signals into electrical signals is put forward in this paper.In this way,the problem of the effective coupling of s pace light to optical fiber is avoided. In order to achieve the purpose,the PIN photodiode array receiver is designed.Ea ch PIN photodiode can independently receive the space laser and convert it to electrica l signals. Multiple PIN photodiodes are arranged in series and parallel so that the electri cal signal could be convergenced for the facility of the subsequent signal processing.After that,bot h the theoretical analysis and simulation experiment on this new receiver are carried out.The exp erimental results show that the new receiver can effectively improve the receiv ing efficiency.