The thermal analysis were carried out on TGA,in which,three kinds of agriculture and forestry biomass of eucalyptus leaves,sugar cane leaves and mulberry bar were chosen as raw materials.By contrasting the TG and DTA curves,the pyrolysis process of biomass was discussed.The activation energy of biomass pyrolysis under different temperatures was obtained and the reaction order of biomass pyrolysis were determined by dynamic analysis based on Coats-Redfern integral method.The results showed that:The thermal decomposition process can be divided into four stages,including drying,preheating,thermal decomposition and carbonization.Especially,the thermal decomposition in the temperature range of 300-400 ℃ was the most violent,the raw material was decomposed rapidly and a large amount of heat was released.The dynamic model while n=2,3could effectively describe the thermal decomposition of the biomasses.The activation energy of thermal decomposition reaction of three kinds of biomass during the low temperature stage is higher than that of the high temperature stage,that is EsEmEe.