The invention discloses a testing method of an anchor mouth in an anchor pulling test. According to the testing method disclosed by the invention, through changing the position of a touch point of an anchor rod and the anchor mouth, a modifying starting point, a modifying finishing point, a maximum modifying depth point and a maximum modifying longitudinal profile of the anchor mouth are obtained, and the modifying starting point, the modifying finishing point, the maximum modifying depth point and the maximum modifying longitudinal profile of the anchor mouth are used for guiding modifying work of the anchor mouth in the anchor pulling test, so that the modifying of the anchor mouth is standardized and targeted, and the modifying workload of the anchor mouth in the anchor pulling test is greatly reduced, the modifying time of the anchor mouth in the anchor pulling test is greatly shortened, and the cycle of the anchor pulling test is effectively reduced; and besides, the whole test process is simple, convenient, and controllable, test data is easy to sort and extract, and the test result is genuine and believable.