The invention discloses an efficient steam boiler for gasification and combined combustion of pulverized coal, comprising a blast blower, a pulverized coal bunker, a pulverized coal transmission pipe, a combustion chamber, a gasification chamber, a hearth, a horizontal flue, a steam superheater, a tail shaft and a boiler support, wherein the blast blower is connected with the pulverized coal bunker, and connected with the gasification chamber through the pulverized coal transmission pipe; a combustor is connected with the gasification chamber; the gasification chamber, the hearth, the horizontal flue and the tail shaft are connected in order, and arranged on the boiler support to form an inversed U shape; a non-combustion zone is arranged above the joint of the hearth and the gasification chamber; the hearth is provided with a jet flow air inlet and a secondary air inlet at the bottom; the outlet of the non-combustion zone is provided with a tertiary air inlet; the steam superheater is arranged in the horizontal flue; and the tail shaft is internally provided with a coal economizer and an air preheater. The efficient steam boiler for gasification and combined combustion of pulverized coal disclosed by the invention saves space, reduces dust emission, realizes gasified transmission, and stabilizes combustion; and the burn-off rate of the pulverized coal is above 99%, and the heat efficiency is above 93%.