Abstract: The leakage of tank oils, once occurred, will bring about adverse effect to ambient environment, social economy and safety of tank farm, and even cause safety accident. Herein, the leakage diffusion process of oil and gas was simulated with the improved Gaussian puff model to find out the concentration distribution law of oil and gas in tank farm under different environmental wind speeds and atmospheric stability. Meanwhile, the tank farm was divided into the explosive hazardous area, flash fire hazardous area and suffocation hazardous area according to the risk level of oil and gas concentration. By analyzing the influence of environmental wind speed and atmospheric stability on migration and diffusion of oil and gas puff, the influence law of environmental conditions of tank farm on concentration distribution of oil and gas, as well as the scope of hazardous area, was obtained. Specifically, the migration and diffusion of oil and gas puff is intensified with the increasing of environmental wind speed, but the concentration of oil and gas in the tank farm is reduced, and the hazardous areas of different grades are reduced accordingly. With the increase of atmospheric stability, the diffusion of oil and gas puff becomes weaker, the influence range of concentration along the downwind direction increases, but the influence range along the crosswind direction decreases. Because of the fluctuation of wind speed, the oil and gas puff may gather and form an oil and gas accumulation area at high concentration. Generally, the lower the environmental wind speed and the more stable the atmosphere, the easier the oil and gas puff to gather. The improved Gaussian puff model may more accurately reflect the leakage diffusion law of oil and gas, and predict the concentration distribution of oil and gas, which could provide guidance to the safe operation and management of tanks.