Hammer test is a common method for bolt nondestructive dynamic test, but the potential error reading from the wave pattern frequently occurs due to the inconsistent wave caused by the small impact area. The engineer dynamic detection is therefore of great significance in analyzing the hammer mechanic properties. In this paper, the impact between the hammer and the pole was simulated as a spring whose stiffness is K and whose mass is zero, so as to probe into the local deformation. Then the expression of the impact force and the pulse time during the impact were derived. The ANSYS/LS-DYNA software was used to simulate the stress wave pattern and the pulse width in the process, as the hammers had different masses and the radius of impact head and its elastic modulus had different impact velocities, and the prestressed bolt was excited by hammers with different masses and different hardnesses in laboratory. The results further describe the mechanics of the impact of the hammer and rock bolt and creates the condition for the improvement of the engineering detection quality in the rock bolt nondestructive dynamic detection.