In this paper, finding optimal rotor slot measurements in asynchronous motors has been realized by using optimization methods Sequential Nonlinear Programming (SNP), Genetic Algorithm (GA) and Sequential Mixed Integer Nonlinear Programming (SMINP) and effects of them on the motor performance have been investigated comparatively. The purpose of the work is to obtain the slot geometry that provides maximum motor efficiency. Simulation studies have been done by using Ansys Maxwell package programming. According to the rotor slot geometry obtained from simulation results, the motor model has been created in Ansys Maxwell 2D and required analyses of the motor have been realized. According to the results obtained, the most efficient rotor geometry has been occurred when using GA.