A body coil for an MRI system has a conductor management and a tuning/detuning circuit. The tuning/detuning circuit is connected to the conductor management, and used to subject the conductor management to tuning/detuning control by a control signal. The tuning/detuning circuit has a control signal interface, a switch diode unit and an AC/DC conversion circuit. The control signal interface receives the control signal. There is at least one switch diode unit, respectively series-connected on at least one antenna rod and/or at least one end ring of the body coil conductor management. The AC/DC conversion circuit has a rectifying circuit, for converting the power of an input RF emission signal in the MRI system to a DC current, the DC current being used to provide a DC current for the switch diode unit to be turned on. The body coil reduces the cost of a DC power supply, and this reduces heat generated by the diodes.