In order to simplify the laser communication system, reduce the system volume and the transmission power consumption, a set of spot positioning and data communication integrated system is designed by avalanche photo diode (APD) type four-quadrant detector. The basic principles are introduced, and the hardware design analysis of the key technologies is carried out. The testing platform is built in the laboratory, and the spot positioning accuracy and communication performance are tested respectively. Testing results show that the spot positioning accuracy can reach 1.2 μm and the communication rate is 20 Mbps, which verifies the feasibility of the designed communication system.