step 1, imaging echoes of the multi-channel SAR system based on a linear mapping reconstruction algorithm to obtain a reconstructed high-resolution wide-swath image;

step 2, estimating positions of the azimuth ambiguity regions of the reconstructed high-resolution wide-swath image and defining an azimuth ambiguity detection function r(τ,η) as:

wherein log {·} represents a natural logarithm operation, represents a spatial averaging operation, |·| represents an absolute value calculation operation of a complex number, and L₁(τ,η) and L₂(τ,η) respectively represent two multi-look images obtained by performing azimuth double-look on a reconstructed high-resolution wide-swath image, τ represents a range fast time and η represents an azimuth slow time;

step 3, extracting ambiguity images in the azimuth ambiguity regions based on channel cancellation and a refocusing algorithm, wherein

a linear combination coefficient ω(f_η)=[ω₁(f_η), ω₂(f_n), . . . , ω_N(f_η)] for the-channel cancellation satisfies the following expression:

wherein ω_n(f_η) represents the linear combination coefficient corresponding to the nth channel, n represents a serial number of a receiving channel, b represents a serial number of a Doppler interval, an azimuth frequency is

a form I_MCC(τ,f_n) of a image I_MCC(τ,η) in the time domain after channel cancellation in a range-Doppler domain is:

wherein p_n(f_η) represents a reconstruction coefficient of the nth channel in a reconstruction process, and I_n(τ,f_η) represents a form of an image I_n(τ,η) in the time domain corresponding to the nth channel in the range-Doppler domain;

ambiguity refocusing and inverse defocusing are realized by phase multiplication in two-dimensional frequency domain, and a calculation method of refocusing is:

wherein c represents the velocity of light, V_τ represents an equivalent imaging speed corresponding to the central range gate of the ambiguity region, f₀ represents a carrier frequency, R₀ represents a nearest slant range, f_τ represents a distance frequency, r⁽¹⁾(f_τ,f_η) represents an intermediate result, R(τ,η) represents a result of refocusing, * represents a complex conjugate operation, ⊗ represents a Hadamard product, K(f_τ,f_η) represents a two-dimensional frequency domain expression of an echo of an ideal point target, FFT2{·} represents a two-dimensional Fourier transform, and IFFT2{·} represents a two-dimensional inverse Fourier transform; and

an image R_Amb(τ,η) corresponding to ambiguity pixels is obtained from a refocused image through classification of a mixed Gaussian ambiguity, and inverse refocusing is performed to obtain a ambiguity image I_Amb(τ,η) corresponding to the ambiguity pixels:

wherein r⁽²⁾ represents an intermediate result; and

step 4, suppressing a repetitive blurred image in an echo of the echoes of the multi-channel SAR system.