Numerical simulation for random inventory system applying Mente Carlo's simulation technology is carried on,moreover system decision is made and optimal solution is arrived after research on relevant sensitive parameter.These results of research confirm that the way of making decision is practicable.Two important conclusions are proved by the data from an example inventory system.One of them is that optimal inventory strategic permit a restrictive short-of-stock policy in the case of paying for decrease because of short-of-stock;the other is that it embodies the ideas of zero-inventory technology and Just-In-Time(JIT).