The invention relates to a wireless on-load vector tester which is used in the field of electric power measurement. The tester includes a voltage reference and a measurement host which adopt wirelesscommunication. The voltage reference and the measurement host are provided with power supplies and realize synchronous measurement calculation of different measurement points based on voltage and current frequency, amplitude, phase and other electrical parameters between the voltage reference. The measurement host can independently work for measurement and calculation of various electrical parameters of three-phase voltage and three-phase current signals, and can also take the voltage reference as a reference for multiple separate measurement, store data, synthesize and calculate all input measurement results with the voltage reference and then directly display a result on a display in a vector diagram for a PT core phase and an on-load vector test. The wireless on-load vector tester is aconvenient and quick hand-held instrument which is suitable for an intelligent transformer station, can measure the amplitude and phase of the signals among different locations, carries out the on-load vector test and directly display a hexagonal diagram.