An analog front-end circuit for multi-meteorological sensors which mainly includes LDO, programmable gain amplifier, SAR ADC, and humidity measurement circuit was designed. The programmable gain amplifier uses all-difference rail to orbit as the main structure to suppress the noise, and the continuous-time Auto-Zero calibration technology is adopted to reduce its input imbalance voltage. For the 14-bit SAR ADC, in order to reduce the average power consumption and area of CDAC, a segmented differential DAC capacitor array based on the VCM-based switching strategy was designed. Finally, based on the principle of the relationship between the capacitance value of the humidity sensor and the frequency of the rectangular wave, a humidity measurement circuit was designed. The frequency error of the humidity measurement circuit is 0.03%. The analog front-end circuit is based on Hua Hong′s 0.18 μm CMOS process, and the circuit design, layout drawing and simulation verification are carried out through Cadence Spectre software. The post-simulation results show that the circuit as a whole can realize the function of amplifying the input analog signal and finally outputting the digital code, its effective number of bit (ENOB) is 11.40 bit, SINAD is 70.37 dB, SNR is 71.05 dB, SFDR is 83.85 dBc, and THD is -78.55 dB.