An　accurate　calculation　method　for　transient　process　of　HVDC　transmission　system　was　proposed　in　this　paper.　Calculation　for　main　HVDC　equipment　and　control　system　were　conducted　separately.　Main　equipment　was　described　in　piecewise　homogeneous　linear　differential　equations　with　solutions　obtained　with　analytical　method.　Control　system　containing　non-linear　courses　was　calculated　with　a　step-changed　integration　method.　Accurate　time-domain　response　was　obtained　by　combining　the　two　methods.　By　using　analytic　solution　instead　of　numerical　integration　method　for　transient　process　in　main　HVDC　equipment,　calculation　process　is　no　longer　be　limited　by　small　step　length,　and　has　no　truncation　errors　and　numerical　stability　problem.　A　typical　example　was　presented　and　analytical　solution　results　were　compared　with　PSCAD/EMTDC　simulation　results　to　verify　validity　andefficiency　of　the　proposed　method.　©　2017,　Power　System　Technology　Press.　All　right　reserved.