The invention provides a well depth measuring device, which comprises a light pulse generator, a counting circuit and a calibration circuit, wherein the calibration circuit is connected with the counting circuit and is used for receiving light pulse from the light pulse generator and regulating the number of the light pulse according to control indications, and counting pulse is formed and is output to the counting circuit to be counted. The well depth measuring device provided by the invention has the advantages that through the calibration of the calibration circuit, the well depth measuring accuracy is improved, meanwhile, the service lives of a driving wheel and a cable can be prolonged, and the resource consumption is reduced.