Abstract: The hit force of the falling rock in an abandoned quarry pit on the north side of Yangshan Mountain of Wuxi City was calculated for geological disaster treatment by three commonly-used calculation methods, namely, subgrade technical manual method, tunnel technical manual method and Yang Qixin method. The comparative analysis show that it's easy to determine the parameters by subgrade technical manual method and its result is relatively reliable, the design thickness of the buffer layer by tunnel technical manual method cannot be directly applied in calculation, when the buffer layer is thicker than 0.3m, the shock time calculated by the method is too long, which does not match with the actual situation, the result by Yang Qixin method is a little lower than actual situation and corresponds with that of subgrade technical manual method. To ensure the safety and reliability of disaster treatment engineering, it is suggested that subgrade technical manual method should be adopted to calculate the hit force of falling rock and that buffer layer combined with falling rock barrier be used to treat the rockfalling disaster.