This paper constructs and simulates the interface circuit of a temperature sensor based on SMIC 0.18 μ m CMOS. The simulation results show that when the power supply voltage is 1.8 V, the chopper op-amp gain is 89.44 dB, the low-frequency noise is 71.83 nV/Hz, 1 / 2 and the temperature coefficient of the core temperature sensitive circuit is 1.7808 mV/ ∘ C. The sampling rate of 10-bit SAR ADC was 10 kS/s, effective bit was 9.0119, SNR was 59.3256 dB, SFDR was 68.7091 dB, and THD was −62.5859 dB. The measurement range of temperature sensor interface circuit is −50 ∘ C ∼ + 1 2 5 ∘ C, the relative temperature measurement error is ±0.47 ∘ C, the resolution is 0.2 ∘ C/LSB, and the overall average power consumption is 434.9 μ W. [ABSTRACT FROM AUTHOR]