Abstract: In gaspuff Zpinch experiments, the snowplow model, one of the simplest and commonly used models, has been used to predict the implosion time from the generator current parameters, the load mass per unit length, and initial radius of annular gas load. After analyzing the physical model, the onedimensional motion equation and it's solutions in different configuration of the annular gas column are discussed in this paper. According to these formulas, the calculated Zpinch imploding time arriving at the certer are compared with the values of the three typical experiments(on Gamble Ⅱ, DoubleEAGLE and BLACKJACK5 respectively) with current 1.21~3.0MA. The comparison shows that the snowplow model is a tool in prediction of some experimental results to optimize the load parameters like t