In order to meet the monitoring and warning of medium-small scale disastrous weather in the power grid and solve the problem of inefficient monitoring of transmission line meteorological monitoring devices, this paper proposes the overall architecture and software and hardware construction scheme of the micro-meteorological online monitoring system for transmission and transformation power stations. Focus on the analysis of the system architecture and the functions of each module of the system, study the comprehensive assessment model of flood control risk and the flood control risk prediction model, and use the micro-meteorological monitoring data to assist decision-making in the whole process of flood control. Taking a provincial construction scheme as an example, the effective application of the method is verified.