In order to ensure the safe operation of underground gas storage and play an important role in seasonal peaking and emergency gas supply as well as strategic reserve, it is necessary to analyze the risks of gas storage seals, surface facilities and wellbores, which involve the whole life cycle of design, construction and operation. Among the traditional risk assessment methods, the risk matrix method was widely used, but there are problems of strong subjectivity and vague definition of risk level. Therefore, a quantitative grading assessment method for gas storage risk based on risk matrix-K-means (RM-K-means) was proposed, the complex network node importance was introduced. Taking the Xiangguosi gas storage facility in Chongqing as an example, the quantitative grading assessment of the whole life cycle risk was performed by the RM-K-means-based method. The results show that the focus should be on organisational management during the design phase, construction technology and professional quality of personnel during the construction phase, and equipment integrity and operating conditions during the operation phase. Compared with the traditional risk matrix method, the RM-K-means-based method can improve the classification capability of high risks by 100% and low risks by 62. 3%, which improves the conformity of risk assessment, provides quantitative data support for the risk matrix, and provides support for risk management and accident prevention throughout the life cycle of gas storage. [ABSTRACT FROM AUTHOR]