The digitalization of basic equipment is the basic requirement for the development of intelligent power plants.In order to realize remote monitoring and automatic reading of base type liquid level meters,a liquid level measuring system based on digital image processing is proposed.Image processing algorithms include color threshold segmentation,improved Canny edge detection and template matching and window search peak detection,which is new proposed.Instrument location,level interface extraction,digital recognition and camera self-calibration are respectively performed on the captured images,finally realizing the digitization of liquid level image.At the same time,the system has the function of adaptive median filtering,histogram concavity analysis and perspective distortion self-correction,improving its noise resistance and adaptive performance.As laboratory tested,the measurement system has good accuracy and can maintain the accuracy level of the original instrument.