The invention discloses a monitoring system and a method for operation of a power transmission network. The monitoring system for the operation of the power transmission network comprises a monitoring module, a judging module and a warning module, wherein the monitoring module is used for monitoring the power transmission network to obtain a monitoring result, the judging module is used for judging whether the monitoring result meets a preset condition, and the warning module is used for generating a warning signal when the monitoring result does not meet the preset condition. Through the monitoring system and the method, the operation of the power transmission network is monitored in real time, and the warning signal can be generated when the power transmission network cannot operate normally, so that monitoring and maintenance staff of the power transmission network can handle problems of abnormity timely.