Since　the　magnetic　flux　in　the　PM　is　unevenly　distributed　and　the　internal　working　point　of　PM　is　different　when　providing　forward　and　backward　exciting　currents　to　the　coil　of　PM　contactor,　an　equivalent　method　was　proposed　that　partitioning　the　PM　along　the　magnetization　direction　based　on　different　magnetic　flux　density　of　the　cross　section　of　magnetic　circuit　of　the　PM.　A　monostable　PM　contactor　with　single　coil　was　used　as　an　example.　Its　magnetic　flux　density　under　different　exciting　current　conditions　was　analyzed　by　building　an　equivalent　magnetic　circuit　model　of　the　contactor.　Comparing　the　calculated　value　with　measured　value　of　attractive　force　of　movable　core　under　different　working　circumstances,　the　result　demonstrates　that　the　calculation　error　of　the　calculated　value　of　attractive　force　is　less　than　10%,　which　shows　the　correctness　and　validity　of　the　method　of　building　an　equivalent　magnetic　circuit　model　by　partitioning　the　PM.