This paper discusses study of design and simulation of series compensator for improving power quality and reduces the harmonic distortion of sensitive load. Electronic device and control technologies have made it possible to mitigate power quality problems &maintain the operation of sensitive load. The use of a series compensator (SC) to improve power quality is an isolated power system is investigated. The role of the compensator is not only to mitigate the effects of voltage sag, but also to reduce the harmonic distortion due to the presence of non linear loads in the network. The series compensator consists of injection transformer, filter, ESS, VSI, & control. In SC LC filter can be achieved by eliminating the unwanted harmonics. The ESS can be a capacitor of suitable capacity. The modelling and simulation of the proposed series compensator was implement in matlab simulink work space .Simulation results verify that the SC is effective in reducing the harmonic distortions and thus improving the supply quality of isolated power system.