With the improvement of biochemical technology and the increasing demand of biochemical products, higher and higher requirements are put forward for the large-scale, energy-saving and efficient fermentation tank. The energy consumption of stirrer in fermentation tank accounts for more than half of the whole production line, so it is very important to select the appropriate agitator (size and type combination) for large fermentation tank. The scale-up of agitator is a complex problem related to the technological process. Previously, it can only be scaled up step by step through experience. According to the amplification criteria obtained, it can be extrapolated to industrial scale. With the continuous development of computational fluid dynamics (CFD) technology and high-performance computer, the use of CFD technology to design large-scale fermentation tank has become the main trend.