The formation process of shaped charge jet was analyzed and the models of all the phases in the formation process were proposed. The detonation of explosive, the interaction of the explosive with the metal liner, the collapse of the liner, and the formation of the jet and slug were taken into account in the models. A calculation of a specified shaped charge was conducted on the basis of the model, and the results conformed to the data from experiment. It shows that the collapse velocity of the peak and the bottom of liner is smaller than that of the middle of liner and therefore the reverse velocity gradient is formed. It can be concluded that the models can be used in the engineering design of MWS and the calculation of penetration parameters.