Abstract: For the tripping phenomenon existing in bolt tail screw connection, numerical simulation and laboratory test are used to study the influence of different strength, tooth height, thickness and shape of nuts on screw joint when the bolt yield strength is 500 MPa. The paper analyzes the influence of flange nuts with nut strength level of 5, 6 and 8, tooth height of 0.6H, 0.7H, 0.8H and 0.875H respectively, thread thicknesses of 24 mm and 30 mm on screw joint. The results show that when bolt yield strength is 500 MPa, the nut strength level is not less than 6, the tooth height is not less than 0.7H, thickness of 24 mm nut can meet the needs of bolt strength, and flange nuts will make each turn stress of thread more even.