Aimed at the limitation of conventional deceptive jamming in the CRPJ-SAR (chirp rate polarity jittered SAR), the sub-Nyquist sampling repeater jamming against CRPJ-SAR was investigated. The signal model of truncated sub-Nyquist sampling repeater jamming was built and the jamming effect of sub-Nyquist sampling repeater jamming on CRPJ-SAR was analyzed. Analytical formulas to calculate the number, location and amplitude of false targets were given and the various jamming effects with different sampling intervals were also addressed. The correctness of theoretical analysis was validated further by the simulation experiments.