In the field of geological engineering, monitoring the long-term fluctuation of groundwater level using drilling holes is a valuable technique for groundwater level assessment. There are many methods to measure the groundwater level of drilling holes. The common methods are rope measurement method, resistance measurement method and photoelectric measurement method. Today, I will focus on how to use photoelectric measurement methods to monitor the channel groundwater level in geological engineering projects. The method involves using the electronic device to determine the water surface location by acoustic and optical signals, and then quantifying the groundwater level using the scale or photoelectric signal.