This paper analyzes the effect law of reactive power compensation device in medium voltage distribution network to PLC channel characteristics, in order to achieve application of PLC to provide the theoretical basis and reference. The analysis of medium voltage distribution network existing compensation mode and compensation device indicates that the distribution transformer low-voltage centralized compensation and the user terminal dispersion compensation of reactive power device for medium voltage PLC channel characteristics influence can be ignored. On the analysis of substation centralized compensation and reactive on dispersion compensation in two ways, it focuses number of reactive power compensation equipment, capacity, compensation position on the influence of carrier signal transmission characteristics and input impedance. The results of the study indicate if there is compensation device is accessed to compensation point directly, voltage attenuation amplitude increases with the compensation capacity and the number of compensation point increase, and largely independent of position compensation; if the reactive compensation device is connected to the compensation point after a certain length of cable, the influence of the above factors on the voltage decline is negligible. This work is supported by Fundamental Research Funds for the Central Universities (No. 2016MS90).