The invention relates to a device and a method for realizing the nuclear magnetic resonance radio frequency received signal digital down conversion, which are realized on the basis of the FPGA technology, the device comprises a DC-offset suppressor, a command decoder, a numerical controlled oscillator, a real part channel, an imaginary part channel and an output control interface, wherein, the DC-offset suppressor suppresses the DC-offset which is generated during the digital signal processing process; the command decoder decodes control words of the numerical controlled oscillator, the related control words of a CIC comb filter and the control words of a DDC output in a real-time manner; the numerical controlled oscillator decodes the control words of the numerical controlled oscillator in the real-time manner; the real part channel and the imaginary part channel complete the orthogonal detection operation of a digital nuclear magnetic resonance free induction decay signal from the radio frequency signal to the baseband signal; and the output control interface realizes the data communication with a follow-up digital signal processing module or a data memory. The device has strongpracticability and can be flexibly updated according to user needs, thereby avoiding the crises that the whole product can not be continued or the production of the whole product is stopped due to the termination of the life cycle of key components, etc.