Abstract: The displacement damage caused by the space energetic particles would result in the degradation of parameters of photoelectric coupler devices onboard spacecraft under the related space environment, such as the saturation voltage drop, the current transfer ratio, the breakdown voltage, and the forward voltage, and even leads to the device failure. In order to study the effects of the displacement damage on the photoelectric couplers under the LEO neutron irradiation, the electrical properties of different types of optocouplers are tested under the neutron irradiation. The variation trends of the parameters such as the saturation voltage drop, the current transfer ratio, the breakdown voltage and the forward voltage under different fluences of the neutron irradiation are obtained. It is shown that the saturation voltage drop, the current transfer ratio and the breakdown voltage are relatively more sensitive to the neutron irradiation, while the forward voltage is much less sensitive to the same level of irradiation. Analysis reveals that the displacement damage caused by the neutron irradiation is an important reason for the degradation of the device’s current transmission performance. The research results will provide an experimental basis and a reference for the use of photoelectric coupler devices in the space environment.