This paper shows a method for optimization of CHB inverter's harmonic performance under Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) control. The optimization techniques are used for solving the set of non-linear transcendental trigonometrical equations. SHE is implemented to reduce the THD value. The set of non-linear equation is minimized by Big Bang-Big Crunch optimization technique. The BBBC technique is suitable for any number of levels. With the help of this technique third, fifth, seventh and ninth level harmonics have been eliminated. Simulation work is done in MATLAB software and the experimental results validates the theory.