Automatic weather stations generally use capacitive humidity sensors when measuring the relative humidity on the ground. However， these sensors were prone to relatively significant measurement errors in harsh environments such as low temperatures or high humidity. To improve the humidity measurement accuracy， In this paper， a 4-point array humidity measurement system including four humidity sensors， four heating resistors and their measurement and control circuits is proposed， and the error correction is carried out by integrating the sensor heating technology and air pressure control. The error correction equations were established using measurement data at different air pressures and the quasi-Newton method (BFGS) with a global optimization algorithm to achieve error correction. The experimental results showed that the RMS error of the measurements can be reduced from 6.1% to 2.3% at 0 ℃ after correction.