Abstract: During the operation of the steam generator in the nuclear power unit, due to the influence of the corrosion products of the secondary circuit, a large amount of sludge accumulation and scaling will occur on the location of the tube support structure. The commonly used sludge detection method is video inspection. However, due to the dense arrangement of the tubes, comprehensive and accurate information cannot be obtained. Based on the experiment, this paper explored a set of typical measurement method of the clogging rate detection. This method could be used for quantitative detection of scaling of the support plate, and provided a reference for steam generator maintenance and flushing activities during in-service inspection.