The invention relates to an ultrasonic flaw detector with high detection accuracy. The detector comprises a shell, a touch screen, at least two buttons and at least two moving wheels, further comprises a detection mechanism, a clearing mechanism and a central control mechanism, wherein the clearing mechanism comprises a connection port, a pedestal, a polishing block, a switching component, two lifting components and two power components, and the detection mechanism comprises a driving component, a driving shaft, a second gear, a moving block, a transmission bar, a hydraulic cylinder, a connection column and a probe. In the ultrasonic flaw detector with high detection accuracy, with the clearing mechanism, a surface of a workpiece can be processed before detection, thus, the surface of theworkpiece can be kept clean and flat, and detection accuracy of the ultrasonic flaw detector is improved; by the detection mechanism, automatic regulation of a probe angle can be realized, automationdegree of the ultrasonic flaw detector is improved, and detection efficiency of the ultrasonic flaw detector is also improved.