In this article, a microcontroller-based high-accuracy dew-point (DP) instrument using a quartz crystal resonance (QCR) sensor is developed. The sensor is a symmetrical double cooled QCR DP sensor, which has the characteristics of efficient cooling and stable oscillation. Based on the proportional-integral-differential control method, the logic level signal and the oscillation amplitude outputted by the drive circuit are used as control feedback to obtain an optimized expert strategy control system, and the automatic DP tracking measurement is realized by the microcontroller. It is proved by experiments that the measurement error of the instrument in the range of 0-15 °C dew point (DP) environment is less than 0.3 °C DP, and it has a good performance of tracking measurement in a dynamic DP environment.