Abstract: The fast development of computing technology saw wide applications of numerical simulations in underwater explosion in recent years,but it′s still difficult to numerically and exactly predict the damages of a marine structure subjected to underwater shock.It is true that the numerical results and experimental results of a certain underwater explosion problems are in good agreement,but in the most general cases,the problem that how good the numerical results agree with experimental results remain unsolved.In this paper,through three examples,we try to reveal the numerical errors compared with experimental results.All of the three examples show that the numerical errors can be controlled within 30 percent.Two numerical methods,that is,total wave and scatter wave formulations,are employed in this paper.It seems that the total wave method overestimates the effect of cavitations.