Based on the discrete data/accumulation theory of rapid prototyping technology, a method for stealth model design was given to resolve the problem of weight in big-scale stealth model design. Metal model was designed and manufactured by using some discrete frames and cumulate surface for stealth test. The test shows that the model met stealth test requirement, while the model was lighter than 50kg which had characteristic dimension about 5m. This method could gain a light model, and improve precision of radar stealth test and reduce test cost.