In　order　to　achieve　more　accurate　layout　of　voltage　sag　monitoring　devices　and　ensure　the　stable　operation　of　power　grid,　a　multi-objective　optimization　model　of　voltage　sag　monitoring　devices　considering　the　construction　urgency　of　monitoring　nodes　is　proposed.　Firstly,　the　state　estimation　indexes　of　voltage　sag　magnitude　and　voltage　sag　frequency　are　introduced　to　establish　construction　urgency　evaluation　model　of　monitoring　devices.　Then,　comprehensively　considering　the　construction　urgency　of　monitoring　nodes　in　the　power　system,　a　multi-objective　optimization　model　is　established　based　on　voltage　sag　observability　matrix　with　minimizing　the　total　construction　urgency　weight　and　the　loss　rate　of　observability.　An　evaluation　model　of　dissatisfactory　degree　is　introduced,　and　the　computational　model　of　modified　Pareto　optimal　front　is　established　to　analyze　the　coupling　relationship　between　conflicting　objectives.　Finally,　a　practical　transmission　network　with　voltage　level　above　110　kV　is　taken　as　an　example　to　obtain　the　optimal　layout　scheme,　and　the　correctness　and　practical　engineering　application　value　of　the　proposed　optimization　model　are　verified　by　comparison　with　the　traditional　optimization　model.　©　2022,　Electric　Power　Automation　Equipment　Press.　All　right　reserved.