The development of phased array antennas is challenged by the reduction of scan volume due to the appearance of grating lobes. The grating lobes appear in visible space as the spacing between elements be grater than half wavelength. The need for enlarging the spacing between elements is important either for reduction of mutual coupling or filling specific aperture size with small number of antenna elements. These grating lobes should be reduced or eliminated for enlarging the scan space. Nonuniform spacing between elements is an effective method for reduction of grating lobes as it breaks the periodicity of the array which is the reason of grating lobes. This method will be optimized using genetic algorithm implemented using MATLAB. The reduction is -9.7 dB for 8-elements and -12.4 dB for 16-elements at 60° scan angle.