Comprehensive　evaluation　of　power　quality　is　very　important　for　the　governance　of　power　quality　issues　and　the　＇quality-based　pricing＇　in　the　power　market　environment;　however,　in　the　existing　methods,　the　change　process　and　trend　information　on　power　quality　indicators　are　rarely　taken　into　consideration,　and　the　massive　monitoring　data　accumulated　by　the　power　quality　monitoring　system　are　not　fully　utilized,　thus　it　is　difficult　to　reflect　the　overall　situation　of　power　quality　over　a　long　period　of　time.　Therefore,　on　the　basis　of　fuzzy　comprehensive　evaluation,　we　introduced　data　envelopment　analysis　(DEA),　established　a　comprehensive　evaluation　model　of　power　quality　on　a　long-term　scale,　and　put　forward　the　concept　of　＇comprehensive　deviation　degree　of　power　quality＇,　which　directly　reflects　the　deviation　degree　and　trend　information　about　power　quality.　Finally,　a　case　study　show　that　the　proposed　method　can　be　used　to　obtain　the　comprehensive　evaluation　results　on　a　long-time　scale,　and　to　reflect　the　overall　situation　and　trend　information　of　power　quality　monitoring　data.　©　2021,　High　Voltage　Engineering　Editorial　Department　of　CEPRI.　All　right　reserved.