A method and device for controlling a fermenting process, wherein the method comprises collecting samples of biological cells from a fermenting tank, obtaining the state information of the current biological cells based on the collected samples, comparing the state information of the current biological cells with preset target status information to obtain the difference between the state information of the current biological cells and preset target state information, and controlling the feed rate of nutritional solution into the fermenting tank. Real time control of biological fermenting process is thus accomplished based on the state information of the biological cells during fermentation, and the consistency during fermentation is improved. Complicated mathematical modeling and man-made data analysis are not required for the method and device. Real time control of biological fermenting process is accomplished based on a feedback loop with simply calculation, and control delay is not created, and automatic control of cells statement in fermentation is achieved.