In this paper, we investigate the leakage and diffusion characteristics of natural gas. As results show, when the natural gas leaks from the pipeline, it jet into the atmosphere in the form of positively buoyant jets. As a result, a hazardous area can appear at an altitude of 150m from the ground. Furthermore, the natural gas has a low concentration near the ground, this means the natural gas is less harmful to human body. In addition, the wind should be considered in the transport of leaked natural gas.