A fruit grain beverage liquid mixing tank was designed in this study, including the structure of the cylinder block and the mixing paddle, and related parameters were provided. The numerical simulation was carried out by orthogonal test and FLUENT,to determine the influence degree of the factors, such as the installation height of the agitator, the diameter of the impeller and the rotation speed of the propeller, and the parameters of the stirred tank, were optimized to obtain the optimal parameter solution. Results: The main order of the factors that influenced the stability of the agitator concentration was as follows: the diameter of the paddle, the stirring speed, the height of the lower paddle. The results in the present study could provide contribution to the follow-up design of fruit juice beverage filling machine.