The invention discloses a robot casting production line capacity optimization method. The method comprises the following steps of S1, obtaining the relevant parameters of working procedures on a robot casting production line, and setting the number of working sections; S2, setting the number of process distribution schemes, generating the variables by using a chaos sequence, mapping the variables into corresponding process numbers, then setting constraint conditions, and distributing the processes in the set working sections to obtain a process distribution scheme; S3, constructing a double-objective optimization model of the robot casting production line; and S4, respectively substituting the multiple process distribution schemes into a double-target optimization model of the robot casting production line, and calculating an optimal solution. According to the invention, the existing working procedures are reasonably distributed to each set working section, and a process distribution scheme that the balance rate is as high as possible and the smoothness index is as low as possible is calculated by utilizing the set double-target optimization model, so that the load of each section on the production line is balanced to the maximum extent, the production efficiency is improved, and the capacity optimization of the production line is realized.