The invention relates to the technical field of PLC input and output module channel detection, especially to a device for testing the conversion precision of a PLC input and output channel. The devicecomprises a test terminal board and a movable contact module, a row of conductive strips are arranged on the front surface of the test terminal access plate, two conductor slides are vertically disposed on the back surface, and the conductive strips are in one-to-one correspondence electrical connection with the test terminals of the test terminal board, and the two moving conductors are vertically moved along the respective conductor slides to achieve communication of the conductor slides and any conductive strip to access the current loop formed by any two test terminals on the test terminal board into the electrical signal test instrument. The device for testing the conversion precision of the PLC input and output channel simplifies the test process of the PLC input and output channelconversion accuracy to avoid the operator's mistakes caused by clamping the test terminals by mistake, the test results are accurate, the test process saves time and effort, the test equipment damagecaused by improper operation is avoided, and the operation is safe.