A novel sampling distortion cancellation circuit utilizing dual-plate sampling for high-precision differential SAR ADCs was proposed. To eliminate the signal distortion caused by the sampling switch’s on-resistance, the sampling circuit consisted of two paths, whose components’ size were proportional to the other, and the error charges of two ends of the differential were cancelled by subtraction between the two paths. Compared with traditional top-plate sampling or bottom-plate sampling, the dual-plate sampling amplified the amplitude of differential input, avoiding the attenuation of the input caused by the subtracting. Simulation results showed that the THD of the proposed sampling distortion cancellation circuit was reduced by 15 dB and the SFDR was increased by 19 dB at 1 MS/s sampling rate and 300 kHz sinusoidal input signal. The SNR of the sampling circuit was 112 dB.