The power quality assessment method of paralling wind farm was studied in this paper. The effects of the interconnection of wind power on power quality were brief analyzed first. According to the relevant national standards, the power quality evaluation index and its calculation method of paralling wind farm have been given. The method and its steps for calculating the voltage deviation, harmonic current and voltage and the voltage fluctuation and flicker caused by wind power interconnection had been put forward. The evaluation method and the concrete implementation steps had been illustrated based on the actual data of a wind farm. This paper provides a reference basis for the evaluation of the power quality of the interconnected wind farm.