China-Myanmar oil and gas pipeline in Southwest China guarantees the energy security of China. Due to poor geographical circumstance, the safety of pipelines is seriously threatened by natural disasters. After the oil pipeline is damaged, the rapid prediction of the crude oil leakage path and diffusion range is of great significance to the leakage rescue work. In this paper, the real mountain terrain is constructed based on the digital elevation model, the leakage path and diffusion range are described based on the fluid particle tracking method, and a fast leakage prediction method is proposed. By using this method to calculate the various working conditions of mountain pipeline leakage, the different characteristics of the leakage path and scope under various terrains are studied, and the effects of various influencing factors on the leakage are obtained. It provides an effective reference for the rescue work of oil pipeline leakage in mountainous areas.