The invention provides a radio frequency self-interference eliminating system applied to a same-time and same-frequency full-duplex system. The radio frequency self-interference eliminating system comprises a direct modulation laser device, a variable optical delay line, a variable optical attenuator, and a balanced receiver, wherein the upper branch of the direct modulation laser device is connected with the first input end of the balanced receiver, while the lower branch of the direct modulation laser device is connected with the second input end of the balanced receiver via the variable optical attenuator and the variable optical delay line in sequence; the variable optical delay line is used for matching time delays generated by a self-interference signal passing through different paths; the variable optical attenuator is used for matching the magnitude of the self-interference signal; and the balanced receiver is used for receiving two optical signals from the upper branch and lower branch of the direct modulation laser device, performing subtraction, obtaining the available optical signals and then converting into corresponding electrical signals to output. According to the system, the radio frequency signal is modulated by using the direct modulation laser device with low cost, the self-interference signal is eliminated by the balanced receiver, and the good interference eliminating performance and inhibiting performance are obtained in a relatively wide frequency band range.