This paper describes the calculation step and formula of the random simulation of SPR test for the spread of impact point of missle.We do the random simulation of sequential truncated and untruncated testing methods for standard deviation of impact point by DJS-130 computer and analyse the results at the same tine.The analysis shows that the OC function L^*(σ)obtained by random simulation has the precedence over L(σ)obtained by approximate formula.However,E^* _σ(n) is larger than E_σ(n).Hence when we select parameters α、βand λ,it is preferable to use L^*(σ) and E^* _σ(n), and to consult L(σ) and E_σ(n) at the same time. This paper also discusses the scheme of sequential truncated method and presents the opinions for some problems.