In order to study the formation mechanism of explosive welding wave interface, the interface morphology and the welding processes were analyzed by means of explosive welding experiment and numerical simulation. The results show that the plates with lower initial strength are more likely to form periodic wave interface when the welding paremeters are within the weldable window, and the molten material within two wavelength after the collision point still with a high velocity and continues the movement along the interface. However, the plates with higher initial strength and smooth surface are difficult to form wave interface. The results indicate that the formation of the wave interface requires the accumulation of disturbance to trigger the Bahrani enching mechanism. In addition, the molten metal within two wavelength after the collision point will continue to move along the interface and eventually form a stable interface wave eventually.