Abstract: Aiming at the problems of model Ⅰ biomass briquette boiler, such as higher firing space temperature, higher fume temperature, more thermal loss, its design was improved, and model Ⅱ biomass briquette boiler according to the specialty of biomass briquettes combustion was designed and made. By testing two boilers' thermodynamic and environment performance. It indicated that model Ⅱ biomass briquette boiler had higher thermodynamic efficiency, lower firing space temperature, less heat radiation loss and fume thermal loss than model Ⅰ biomass briquette boiler.