The aim of this study was to accurately control the temperature of the fermenter during the beer production process through determining the PID parameters. To solve the problems of the randomness in selection of PID parameters in the site commissioning process of temperature control of the fermenter, genetic algorithm was used to set the PID parameters, and the Matlab and WINCC communication based on OPC was used to realize online tuning and monitoring of data. PID parameters set by the genetic algorithm were as following. The rise time of the output response curve was 2.81 s， the overshoot was 9.12%, and the adjusting time was 5.22 s. The PID parameters set by the genetic algorithm were effective, with fast response, low overshoot and short adjusting time, which met the requirements of field control.