Abstract: Ultrasonic testing was done to detect the defects around R corner in old crankshaft before remanufacturing. According to the characteristics of material and construction of the crankshaft, appropriate probe was applied and special calibration block was designed to locate the defects, then the equivalent method was used to quantify the defects. The results indicate that the defects around R corner in old crankshaft can be located and quantified by ultrasonic testing if the appropriate parameters are used. Moreover, the technique is successfully applied to the practical engineering testing.