The problems of the high exhaust gas temperature in the biomass boiler which moves normally are analyzed，and the anti-balance method to get the boiler efficiency is used to get the relationship between the exhaustgas temperature and the boiler efficiency． The greater exhaust gas heat loss，the smaller the boiler efficiency． Ac-cording to 35t / h biomass grate boiler，the factors which affect exhaust gas temperature are analyzed and summa-rized，and the measures to optimize exhaust gas temperature when the boiler moves normally or is closed to overhaulare taken for responding to the national energy policy． Finally，the exhaust gas temperature has been controlled ef-fectively and the boiler efficiency is improved．