In view of the diversity of domestic solid waste calorific value，there will be some problems such as fuel calorific value is not suitable for the incinerator introduced from abroad． In this study，the adaptability modification of a 350 t /d grate waste incinerator in Guangdong was carried out and based on the bed FLIC calculation software and computational fluid dynamics software Fluent，the combustion in garbage incinerators of different structures was simulated to predict the distribution features and fuel adaptability of the temperature field，velocity field and the gas composition of the front wall folding flame angle and arch u-shaped angle of furnace． The results show that: eliminating the front wall flame angle and the U-shaped angle of the rear arch makes the combustion area of the furnace move down; when the high temperature area is between the grate and the secondary air outlet，the furnace combustion is more sufficient，effectively reducing the output of NOx，saving the amount of out of stock reductant and resulting more suitable mixed combustion of sludge and garbage． Besides，adding 5% LD-40 sludge can effectively reduce the production of CO，CO2 and furnace temperature and slow down the high temperature corrosion phenomenon． The average error between the numerical simulation results and the measured temperature is less than 5% ．