In this study, based on risk matrix theory, the meteorological risk assessment method and process of major activities were established.Taking one major celebration event held in Beijing as an example, the meteorological risk sources during the activities were determined by multiple departments.Using the meteorological data of long-term series and observation data of short-term wind radar, probability analysis of the meteorological risk during the activities was performed.Considering the serious consequences for the activities caused by the meteorological risks, the meteorological risk assessment and risk control research were carried out using the risk matrix.The results show that the main meteorological risks during the major activity were precipitation or cloudy day, daytime high wind, fog and haze, night high wind, high temperature, thunder and lightning, and low temperature.Precipitation or cloudy day, daytime gale, fog and haze are high risks, while night gale is moderate risk, and the remainder are low risks.Finally, the risk control principles and detailed measures were proposed according to the evaluation results, and were successfully applied during the celebration of the major activity.Compared with the weather risk assessment in the existing meteorological business services, this study achieved the transformation from considering the occurrence probability of high impact weather to risk assessment based on impact to major activities.