Air-drying-DCPD-type　unsaturated　polyester　resin　prepared　by　using　modified　hydrolysis　addition　method　was　proposed　in　this　paper.　By　virtue　of　theoretical　analysis,　IR,　and　NMR,　the　mechanism　of　synthesis　reaction　and　the　optimal　technological　conditions　were　investigated.　As　a　result,　the　improved　air　drying　unsaturated　polyester　resins,　which　have　excellent　properties　such　as　shorter　gelation　time,　higher　cured　velosity,　higher　mechanical　strength,　greater　hardness　as　well　as　better　thermal　and　chemical　resistances　were　obtained.