Abstract: In view of the current situation of inconsistent conclusions between existing asteroid impact monitoring systems, the linear approximation method used in the change line impact monitoring system was studied, and the conclusion that the deviation of the orbit distribution relative to the theoretical orbit distribution obtained by this method gradually became significant as the orbit propagation time increased. The impact probability of 6 asteroid instances was calculated using the Monte Carlo method. Compared with the results of the existing Monte Carlo impact monitoring system, the maximum difference is 2.1 times the standard deviation. The impact samples of asteroid 2020 VV in October 2056 are analyzed in detail, and the distribution of impact samples with time and space is depicted, and the conclusions are consistent with those of existing impact monitoring systems. As for the comparison between the different impact monitoring systems, it is concluded that the Monte Carlo impact monitoring system and the change line impact monitoring system currently have their own advantages and disadvantages: the former does not introduce the error caused by the linear approximation method, but the computational cost is high. The linear approximation method used in the latter will bring errors, but it can find some virtual impact sources with low impact probability that may be missed by the former, and the computational cost is relatively low.