DZL single drum chain grate biomass boiler structure is compact, compared with the same type of boiler, small size, save the boiler room infrastructure investment. The boiler adopts threaded smoke pipe to strengthen heat transfer and improve heat transfer coefficient and thermal efficiency. Because the flue gas in the pipe has a disturbance effect. The smoke pipe is not easy to accumulate ash, play the role of self-cleaning. The double-layer secondary air design improves the ignition conditions of biomass fuel. The independent air chamber is adopted to achieve reasonable air distribution, so that an aerodynamic field conducive to combustion is formed in the furnace and the combustion temperature is high.