In　recent　years,　the　problem　of　surface　discharge　of　insulating　materials　caused　by　condensation　and　pollution　has　become　prominent.　Therefore,　it　is　of　great　significance　to　study　the　discharge　initiation　characteristics　of　insulating　material　surfaces　under　wet　and　dirty　conditions　to　improve　the　operational　reliability　of　electrical　equipment.　Firstly,　based　on　the　existing　condensation　growth　model,　a　condensation　growth　model　considering　the　influence　of　the　surface　contamination　layer　is　established,　and　the　visualization　dynamic　image　of　the　whole　process　of　condensation　growth　is　realized　by　MATLAB　software　programming.　Secondly,　the　physical　model　of　a　single　droplet　on　the　surface　of　the　epoxy　resin　plate　was　constructed　using　COMSOL　software　and　the　electric　field　distribution　on　and　around　its　surface　was　calculated.　Models　with　different　plate　spacing,　dewdrop　radius,　contact　angle,　and　droplet　spacing　are　simulated,　and　the　influence　of　these　factors　on　the　electric　field　distribution　along　the　surface　is　analyzed.　Then,　based　on　the　photoionization　criterion,　a　prediction　model　of　the　negative　DC　corona　onset　voltage　considering　temperature　and　humidity　is　proposed,　and　the　corona　onset　voltage　under　the　above　conditions　is　predicted　and　analyzed.　Finally,　relevant　corona　onset　experiments　were　carried　out　to　verify　the　validity　of　the　prediction　method　of　negative　polarity　DC　corona　onset　voltage.　©　2022　IEEE.