The invention discloses a device for eliminating local oscillation leakage. During operation, the device comprises: generating an intermediate frequency auxiliary signal with adjustable amplitude and phase in a baseband digital domain and converting the intermediate frequency auxiliary signal into an analog radio-frequency modulation signal; converting the intermediate frequency auxiliary signal into a negative local oscillation signal with the frequency and amplitude identical to those of a local oscillation leakage signal and the phase opposite to that of the local oscillation leakage signal; and offsetting the negative local oscillation signal and the local oscillation leakage signal to realize the function of eliminating local oscillation leakage. The device can carry out dynamic adjustment of signal amplitude and phase in a digital domain through the adoption of a trial-and-error method according to the offset local oscillation leakage state till the local oscillation leakage signal meets requirements. Because the signal offsetting the local oscillation leakage signal is generated in the digital domain, the amplitude and phase of the signal can be adjusted accurately. The device has a simple method and can quickly realize accurate control of local oscillation leakage elimination. In addition, the device does not influence the normal operation of a transmitter during adjustment.