The coupling is one of the core components of rotatable parts in directional polarization camera, which is responsible for transmitting torque and ensuring the high precision operation of the rotating wheel in the instrument. The characteristics of the instrument require that the coupling has small deformation force, long life and high transmission precision. According to these requirements, a parallel line cutting coupling is designed, and the simulation analysis is carried out. Then the performance of the coupling is designed, including deformation force test, long life test and transmission precision test. Test results show that when the camera is installed within the error range, the deforming force is no more than 10.75 N, which meets the needs of bearing in the camera. After the test of start-running-stop for 40000 times, the driving ability of coupling has no obvious drop, the transmission precision is 4.684×10-5, which meets the requirement of the camera at the end of lifetime, and proves that the coupling meets the life and performance requirements of the camera.