Abstract: As one of the most universally-distributed geological disasters in Lanzhou-Chengdu-Chongqing Products Pipeline, unstable rocks can be classified mainly as two types in view of unstable modes, that is, fall unstable rock and slided unstable rock, among which the former will more likely to bring very significant danger to the products pipeline. Taking the typical unstable rock located at the K0510+700 Lanzhou-Chengdu-Chongqing Products Pipelines as an example, qualitative analysis is made in terms of the basic characteristics, damage mechanisms and influence factors of unstable rocks, and the principle of the energy conservation is used to quantitatively calculate the maximum in-depth and impact force when the unstable rock falls. Calculation indicates that the damage from the fall unstable rock on the products pipeline is closely related with its size, the height of fall and contact area to the ground. The bigger the rock is, the higher the fall will be whilst the smaller the contact area to the ground will be accordingly; thus the depth of rock falling into the soil will be bigger, and this brings heavier impact to the products pipeline. This paper proposes relevant measures to eliminate the impact of unstable rocks, which may be referred in preventing against those rocks.