Visual human-machine interaction (HMI) devices are very important in the interaction process between the nuclear Distributed Control System (DCS) and the power plant operators because of their design correctness and integrity, which affect the operational safety of the nuclear power system. Therefore, visual human-machine interaction devices should be sufficiently tested before leaving the factory. Meanwhile, the current problems of manual inspection of these devices are low efficiency and high human error. Therefore, this paper introduces machine vision technology and proposes an intelligent testing method for human-machine interaction device that can replace human to achieve the following requirements, such as automatic observation, automatic information recognition, automatic operation, and automatic judgment. The detailed information about the specific identification research on DCS interactive images is also described in this paper. Moreover, the developed intelligent testing devices, after application in typical projects, which realized fully unmanned automatic testing of nuclear power DCS human-machine interaction equipment. In addition, the application practice shows that the solutions and devices proposed in this study can significantly avoid human errors, improve test quality and efficiency. They have good application value for improving the quality of DCS equipment and ensuring the safety of nuclear power operation.