PI controller tuning with the assumption of linear PWM model leads to unsatisfactory results under varying operating conditions. Optimal tuning of PI gains is required to get the best response of PI controllers. This paper presents a new method for harmonic suppression using particle swarm optimization (PSO) based PI controller (PSOPI) to estimate an efficient shunt active power filter (SAPF). The proposed filter is tested on a 13 bus industrial distribution system. The study system with the 18 study cases are simulated through MATLAB Simulink with different loading condition and single and multi harmonic sources. The results of applying the PIPSO controller are compared with those out of a double proportional controller (DPC). The obtained results ensure the effectiveness of the proposed filter and its superiority in reducing harmonics.