The invention discloses a ferromagnetic resonance detection and inhibition device for a large photovoltaic power station. The ferromagnetic resonance detection and inhibition device comprises an electromagnetic voltage transformer, a sampling voltage regulation module, a data processing module, a control system module and a switching value output module, wherein the sampling voltage regulation module, the data processing module, the control system module and the switching value output module are sequentially connected; an open triangle position of the electromagnetic voltage transformer is connected with a damping resistor; the switching value output module is also connected with a fling-cut switch; and the fling-cut switch is connected with the damping resistor. According to the ferromagnetic resonance detection and inhibition device, whether resonance occurs or not is judged through carrying out sampling conditioning on secondary side voltage of PT and analyzing voltage data of a power distribution network. If the resonance occurs, a control signal is output to drive a switch action of a contactor through communicating with an ARM chip, thereby achieving effective switching of the damping resistor to complete inhibition of ferromagnetic resonance; and resonance information is displayed to an LCD screen, stored into an SD card and uploaded to an upper computer. The ferromagnetic resonance detection and inhibition device has the advantages of being high in response speed, low in cost, low in power consumption and reliable in operation.