100 G SR4 optical module with the advantages of high transmission rate, mature technology and low cost has been widely used in data centers and data communication access networks. The circuit and optical path of 100 G SR4 optical module has been designed with the method of chip on board (COB) packaging technology, and the transmitting and receiving performances of the module is tested by the self-made testing system. Testing results show that the module accords with the characteristics of the agreement and can meet the requirements of 100 m short distance high-speed data communication system.