As　a　regional　power　grid　with　the　highest　penetration　of　renewable　energy,　the　China　Northwest　Power　Grid　is　now　facing　with　the　renewable　power　curtailment.　That　is　caused　by　the　inefficient　energy　utilization,　interest　conflicts　with　thermal　power　generators　and　the　immature　electricity　price　mechanism.　To　address　those　problems,　this　paper　proposes　a　regional　marginal　price　(RMP)　mechanism　in　the　China　Northwest　Power　Grid.　Firstly,　the　locational　marginal　price　(LMP)　in　the　Northwest　China　is　calculated　based　on　the　economic　dispatch　theory.　Secondly,　on　the　premise　of　considering　geographical　location　and　renewable　resource　distribution,　the　Northwest　China　is　divided　into　seven　regions　based　on　the　clusters　of　LMP　values.　Then,　the　RMPs　in　two　typical　days　are　calculated　by　PLEXOS,　which　verifies　the　effectiveness　of　RMP　mechanism.　Finally,　the　benefit　of　RMP　mechanism　in　the　China　Northwest　Power　Grid　is　shown　by　the　comparison　of　three　electricity　price　mechanisms.　©　2019　IEEE.