Abstract: In order to effectively study the relationship between the P-wave velocity and the stress of coal rock, coal rocks with different impact tendency are selected as research objects, and the wave velocity changes at various stress stages under uniaxial loading and cyclic loading conditions are tested. The fitting analysis is carried out. It is found that the wave velocity increases with the increase of stress under uniaxial loading, and there is a power function relationship between them. Under the condition of cyclic loading, the wave velocity and stress increase and decrease at the same time, which conforms to the power function relationship. The first cyclic loading has the greatest effect on the wave velocity. After the first cyclic loading, initial values of wave velocity increase, but initial values and the maximum values of P-wave velocity tend to be stable with the increase of the number of cycles. The essence for the stress change affects the change of P-wave velocity is that the stress changes the internal pore structures of coal rock. When the stress exceeds a certain range, the degree of pore compaction in coal rock reaches the limit, and the influence of the stress on the P-wave velocity is weakened.