A new dual channel optical rotary joint has been proposed by infrared coupling technique to transmit optical signals across rotational interfaces to ensure continuously transmitting signal.The influences of lateral displacement and end separation caused by assembling misalignment on infrared transmission were tested.The test result indicates that when two parts of rotary joint are relatively rotating,the actual transmission rate equals to 1.46 Mbps,which is the same as stationary.As a result,the requirements of mechanical and assemble precision are reduced,and cost of the rotary joint is decreased.