The invention relates to a phasor measurement method without a load. The phasor measurement method is characterized by comprising steps of: providing a signal with fixed voltage and current phases by using a signal generator of a flow test instrument during a primary device flow experiment; then applying the signal directly to both ends of a primary current transformer, and then transmitting a voltage signal through a wireless transmitter device, and performing phasor measurement without a load by using a measurement device with current measurement and wireless voltage acquisition functions at a location where measurement is required. The phasor measurement method can measure the phasor of a secondary current loop and achieves a flow test before a primary device is charged or loaded, and completely solve a problem that a phasor measurement experiment is dependent on the load of the primary device.