Well　control　via　managed　pressure　drilling　(MPD)　is　a　new　and　effective　method　to　deal　with　gas　kicks　and　overflow　problems,　which　includes　two　stages:　initial　control　response　and　circulating　out　of　gases.　According　to　the　gas-liquid-solid　multiphase　flow　theory,　a　MPD　well　control　model　based　on　rapidly　applying　wellhead　back　pressure　method　was　established,　and　a　finite　difference　method　was　used　to　iteratively　solve　the　model.　The　effects　of　pumping　rate　on　the　maximum　wellhead　back　pressure,　maximum　casing　shoe　pressure　and　maximum　standpipe　pressure　were　analyzed　using　the　model,　and　an　optimized　design　method　for　the　pumping　rate　as　the　objective　function　for　well　control　safety　was　proposed.　The　simulation　results　show　that,　in　the　stage　of　gas　circulating　out,　the　standpipe　pressure　remains　unchanged　with　its　maximum　value,　and　the　peak　value　of　the　wellhead　back　pressure　appears　before　the　gas　front　migrates　to　the　wellhead,　while　the　maxi-　mum　value　of　the　casing　shoe　pressure　appears　when　the　gas　front　migrates　to　the　casing　shoe.　The　reasonability　of　using　the　consistence　of　outlet　flow　and　inlet　flow　to　indicate　the　stoppage　of　bottom　hole　influx　can　be　verified　using　the　model.　The　calculated　pressure　values　using　the　model　agree　well　with　the　experimental　results.　©　2016,　Periodical　Office　of　China　University　of　Petroleum.　All　right　reserved.