Abstract: With the high-speed construction of intelligent power grid, a large number of intelligent factors, including sensors, smart meter and renewable energy facilities, will change the structure of power network and increase power grid operation risk. Moreover, power grid structure will become increasingly complex and uncertain factors have an expansion influence under a growing scale of grid. So, transmission system will face greater potential risks. Six aspects of the risks in smart grid system, namely transmission equipment risk, the spare capacity risk, running environment risk, network structure risk, design standard risk and the access risk of renewable energy, are analyzed in this study. On this basis, the fuzzy comprehensive evaluation method is applied to build risk evaluation index system of smart transmission system and the expert’s opinions and the Delphi method are combined to calculate the weight coefficient of various factors. Finally, the comments set are assigned and the fuzzy value of each factor is calculated and then evaluates each factor’s influence degree to the risk of intelligence transmission system.