The spall phenomena induced by intense laser radiation pulse in aluminum target have been calculated with the elastic-plastic model and the hydrodynamic mode1. The results are compared. For the elastic-plastic model the ca1culation is performed by using different fracture criterions，and the effects of them on the results are also compared. In this paper the thresholds of thickness at which the spa1ling is just prevented are obtained in the case when the laser power density and the wave shape are fixed.