Urban gas system major safety risk identification and evaluation method

The invention discloses an urban gas system major safety risk identification and evaluation method. The method comprises the following steps: step 1, identifying risk points, wherein the risk points comprise fire accident risk points and explosion risk points; 2, risk units are divided according to the production units, wherein the risk units comprise a gate station, a high-pressure pipe network, a high-medium-pressure regulating station, a storage and distribution station, a medium-pressure pipe network and a medium-low-pressure regulating station; 3, according to the possible harm of each risk unit, determining the consequence and possibility of the harm, and multiplying the consequence and possibility to obtain the risk of the determined harm; and carrying out risk analysis and evaluation on the storage tank unit with high risk in the natural gas liquefaction storage base by applying a high-risk article, high-risk process, high-risk equipment, high-risk place and high-risk operation risk evaluation model.