The invention discloses a method for extracting local oscillation from a wideband carrier, which comprises the following steps that: a received carrier signal is subjected to limiting amplification to serve as a local oscillation signal of a quadrature modulator for input, and an intermediate frequency signal output by a local intermediate frequency source is decomposed into two paths of orthogonal baseband signals to serve as I and Q signals of the quadrature modulator for input; and the quadrature modulator utilizes the single-sideband modulation characteristic thereof to extract a local oscillation signal Fc-IF or Fc+IF modulated by a single sideband from a carrier. A device for extracting local oscillation from the wideband carrier comprises a local intermediate frequency (IF) source, a limiting amplification circuit, an intermediate frequency signal decomposition circuit and the quadrature modulator; a signal which is output after the carrier signal passes through the limiting amplification circuit is sent into a local oscillation signal input end of the quadrature modulator, the two paths of the orthogonal baseband signals which are acquired after the intermediate frequency signal produced by the intermediate frequency (IF) source passes through the intermediate frequency signal decomposition circuit are input into I and Q signal input ends of the quadrature modulator respectively, and the quadrature modulator outputs the needed local oscillation signal. The method and the device can effectively extract the local oscillation frequency without a bandpass filter within the frequency range of wideband radiofrequency carrier.