The invention discloses a field test method for testing the performance and the secondary circuit of an extra-high-voltage direct-current phase-selecting switching-on device. On the basis of correctly setting the parameters of the phase-selecting switching-on device, the output voltage and current signals of a relay tester are connected in series with the corresponding-phase switch and the corresponding voltage and current loops of a switchyard three-phase circuit breaker. After that, a manual switching-on instruction is issued by an instation SCADA system. When all three phases of switches are in the switched-on state, instation fault wave recording data of a test switch are called. According to the time difference between the current starting point of each phase and the voltage zero-crossing point of a corresponding-phase switch, whether the control effect of the phase-selecting switching-on device meets the requirement or not can be judged. The effective test problem of the performance and the corresponding secondary circuit of the phase-selecting switching-on device can be solved. Based on the method, the hardware cost is not increased and the test wiring is simple and convenient in operation. The correctness of the performance and the corresponding secondary circuit of the phase-selecting switching-on device can be effectively verified.