Abstract: In the light of fire risk existed in high-pressure gas pipelines and based on constant gas release rate and fire model, a computing model for risk areas of the high-pressure pipeline is proposed and comparison with actual value is made. The result shows that maximum error between them is only 4 m.With this model, impact extension of the accident for a all-diameter rupture pipeline canbe determined through calculating pipe's diameter, working pressure and pipe's length. Researches indicate that a risk impact area is proportional to the square root of operating pressure, to the 5/4 power of pipe's diameter and inversely proportional to 1/4 power of pipeline's length. The model can provide a theory instruction for risk management of gas pipelines.