The invention provides a test block for bolt ultrasonic testing and a bolt ultrasonic testing method and device, and relates to the technical field of bolt testing. The method comprises the following steps of: testing slots on the test block for bolt ultrasonic testing through a flaw detector so as to obtain the echo of each slot; adjusting the echo amplitude of each slot to 80% of the height of an oscilloscope of the flaw detector, obtaining an automatic gain value corresponding to each slot after adjustment, and accordingly determining a distance gain compensating curve; testing a bolt to be tested through the flaw detector, and obtaining the crack echo signal of the bolt to be tested; and comparing the amplitude of the crack echo signal of the bolt to be tested with the maximum amplitude of the distance gain compensating curve, and determining whether the crack echo signal of the bolt to be tested is qualified or not so as to judge whether the crack of the bolt to be tested affects the safety of equipment connected with the bolt to be tested or not. The problem that bolts with various sizes and structures are possibly difficult to precisely test through a fixed cross hole in an LS-1 bolt test block at present can be solved.