The harmonic resonance in the power distribution system or in the industrial facilities has been reported. The harmonic termination by installing a shunt active filter at the end of a radial line can suppress harmonic resonance; however, the harmonic voltage distortion along the line may still be significant due to harmonics standing waves. The distributed active filter system, which consists of multiple active filter units deployed along the power line, can effectively reduce voltage harmonics. Based on the pre-determined droop characteristics, the active filter units can share harmonic filtering workload without any communications. In this paper, the distributed active filter system is applied to a radial distribution line and a loop distribution line, which is often used in high-tech industrial parks for enhancing power reliability. This paper provides the theoretic analysis of harmonic resonance, simulation results and laboratory test results to verify the performance of the distributed active filter system. The deployment strategies of active filter units are also presented.