In order to solve the problem that the spatial transient magnetic field of the secondary equipment of the UHVDC converter station is not clear after being interfered by radio，the research on the monitoring technology of the transient magnetic field of the secondary equipment of the UHVDC converter station is proposed. Based on the data acquisition program of the space transient magnetic field of the secondary equipment of the converter station，according to the schematic diagram of electromagnetic radiation，the electric field intensity and electromagnetic radiation intensity of the secondary equipment space of the converter station are calculated. The switching arc is simplified into a straight wire，and the space transient of the secondary equipment is calculated. Combined with the space transient magnetic field monitoring algorithm of the secondary equipment of the converter station，the space transient magnetic field monitoring of the secondary equipment of the converter station is realized. The test results show that the method in this paper can effectively monitor the space transient magnetic field strength of the secondary equipment，and the radio interference level of monitoring the transient magnetic field is between 10~25 dB· μV/m，which meets the requirements of the standard interference level.化等。