Abstract: As a frequent geological hazard in the construction of mountainous area, slope rockfall is a serious threat to the construction and operation safety of railway and other transportation projects. Under the influence of various factors, the trajectory of rockfall has the characteristics of random probability distribution, and its energy state and impact size are closely related to the movement state of rockfall. The realistic description of the trajectory of the rockfall, thus solving its energy state and impact force is the premise and main reference basis for the subsequent targeted development of protective measures. This article summarizes the software that already exists at home and abroad, on the basis of introducing the probability calculation method based on normal distribution, improving the practical model of rockfall trajectory calculation, and compiling a set of rockfall analysis calculation software, on the basis of probability calculation, putting forward the two worst rockfall movement trajectory, using a variety of methods to calculate the most unfavorable rockfall impact. The software has been successfully applied to the rockfall site of Hewu bridge in Gui-Guang Railway, which has achieved good results, and can be applied in the follow-up work points.