Abstract: Frictional sliding experiments with Jinan gabbro and Diancangshan marble are made by the bishear test method. There are two types of stress change in the experiments. Type A: The normal stress on the fault plane is increased first, then it is kept constant and the shear stress is increased until stick-slip happens; Type B: The normal stress on the fault plane is increased first, keeping it constant and the shear stress is increased to a certain value before stick-ship, then the shear stress is kept constant and the normal stress docreased until the happening of stick-slip. The experiments show that the frictional strength of rocks in type B experiments is higher than that in Type A, There is precusory increase of AE rate before stick-slip in Type A, but this has not been observed in Type B. It is suggested that there are two forms of dislock-ing of the locked faults: Dislcking by rushing, the fault movement is caused by an increase of the shear stress; Dislocking by relaxing, the fault movement is caused by a decrease of the normal stress. The form of stick-slip of faults is determined by the path of stress change in fault