A high-resolution and low-power noise-shaping SAR ADC with segmented dynamic element matching (DEM) was designed. It realized a second-order noise-shaping filter with passive gain to enhance the noise-shaping capability. Besides, a segmented DEM circuit was proposed to solve the problem of harmonic distortion caused by the DAC capacitor mismatch to further improve the signal-to-noise-and-distortion ratio (SNDR) of the ADC. The simulation results show that the designed noise-shaping SAR ADC achieves 91.1 dB SNDR at the sampling rate of 4 MS/s and the oversampling ratio (OSR) of 40. The designed ADC consumes 231 μW at 1.8 V supply voltage, achieving Schreier figure of merit (FOM) of 174.5 dB.