The invention relates to a wet-snow electrical conductivity detection method for externally insulated electrical power. The wet-snow electrical conductivity detection method is characterized by including the following steps: building an artificial lab wet snow environment with externally insulated electrical power; building a test model for the electrical conductivity rate of wet snow volume; detecting the electrical conductivity rate of wet snow volume in the artificial lab wet snow environment with externally insulated electrical power and calculating to obtain the electrical conductivity rate of wet snow volume. Through the establishment of the artificial lab wet snow environment with externally insulated electrical power, the model for the electrical conductivity rate of wet snow volume is connected with the detection circuit, thus realizing the detection functions for the wet snow electrical conductivity property of externally insulated electric power. As a complete set of test process system, the method can guide the detection of wet snow electrical conductivity property during snowy weather for different regions and in varying degrees, the method also provides an important reference for snow prevention and the flashover work of circuit.