Abstract: Firing accuracy is one of the primary performance indexes for the missile weapon system.This paper proposes a method for estimating firing accuracy at the area target.Specifically,the hit area circular error probability(ACEP) is defined as an accuracy index for the area target and further a Monte Carlo integral method is designed for calculating ACEP.Theoretical analysis and simulation results show that the definition of firing accuracy is reasonable and the calculating method is simple and accurate.Therefore,conclusions obtained can be applied to the estimation of the firing accuracy and selection of the aiming point for missile weapons shooting at area targets.