Abstract: A new evaluation method for power quality of coal mine was proposed. Comprehensive weight of each power quality index is calculated through linear weighting of objective weight determined by rough set theory and subjective weight obtained by analytic hierarchy process. Matching coefficient between weighted index sequence and reference index sequence of power quality is calculated by use of dynamic time warping method, and evaluation level interval is got, so as to realize comprehensive evaluation for power quality of coal mine. The practical application result verifies feasibility and effectiveness of the method.