In order to decrease the pollution from direct burning of straw, the paper studied on hot water boiler of straw burning for heating plant. The heating plant is consisted of hot water boiler of straw burning and accessories system (i.e., collecting system and pretreatment system). Based on the analyse of straw characteristics (i.e. bulk density, moisture and volatile matter), underfeed stoker and double combustion chambers are introduced in the designing of straw boiler. Test result of thermal performance showed that technical parameters of the heating plant could meet the national standard. It not only has stable, clean and efficient combustion, but also improves the efficiency of straw energy utilization.