In order to research the relationship between the breaking torque, locking torque and pretightening force of hilock bolt connection. The mathematical model of high lock bolt connection was deduced with the help of the common bolt connecting classical theory. With the material A286 of the M5, M6, M8 three point hilock nut and non selflocking hilock nut and hilock bolt as the experimental object,the breaking torque, locking torque and pretightening force were got using torsion testing machine. The torque coefficient was calculated by the mathematical model of the deduction. Experimental results show that breaking torque and torque coefficient of the three point hilock nut and non selflocking hilock nut are almost the same. For three point hilock nut, nosing parts almost have no effect on breaking torque of hilock nut, locking torque is linear superposition to breaking torque. The correctness of the mathematical model is verified by the experimental results.