Safety light curtain has four basic parameter characteristics: optical axis spacing, resolution, working distance, protection height. We should follow the following steps in the selection: the first step: The machine safety risk assessment of the machinery to be protected. The main consideration is the mechanical safety level and the degree of damage that can be caused. Step 2: Select the parameters according to the specific use position of the safety light curtain. Third step: According to their own needs to develop higher technical requirements.