Defect size measurement device and method

The invention provides a defect size measurement device and method. The defect size measurement device comprises a ruler body, a laser displacement sensor and a data acquisition unit, wherein supporting rods perpendicular to the ruler body are arranged at the two ends of the ruler body; the upper end of the ruler body is provided with a linear guide rail in the extending direction of the ruler body; the front face of the ruler body is provided with multiple trigger knobs at preset intervals; the laser displacement sensor is arranged on the linear guide rail in a sliding mode; when the laser displacement sensor slides to the trigger knobs on the ruler body, the laser displacement sensor is triggered to measure the vertical distance between the current location and the surface of an object to be measured; the data acquisition unit is connected with the laser displacement sensor and stores data obtained by measurement of the laser displacement sensor. By the application of the defect size measurement device and method, the instrument error, installation error and operation error can be reduced effectively, it is ensured that measurement data are real and accurate, precision is high, and reliability is high.