Abstract: Using rice husk as raw material and FeCl₃as catalyst,the basic elements and combustion characteristics of rice husk hydrothermal char were studied by elemental analyzer and thermogravimetric method.The effects of hydrothermal temperature and catalyst concentration on the elemental structure and combustion characteristics of rice husk hydrothermal char were investigated.The results show as follows:1)With the increase of hydrothermal temperature,the fixed carbon content and calorific value of hydrothermal carbon increase,while the atomic ratios of O/C and H/C decrease gradually.The addition of FeCl₃further deepens the degree of carbonization of hydrothermal carbon,but the effect of hydrothermal temperature on the degree of carbonization is greater than the concentration of FeCl₃.2)When no FeCl₃was added,the hydrothermal carbon combustion shows double peaks,and the peak value of volatiles is significantly higher than that of fixed carbon combustion.With the increase of hydrothermal temperature,the peak value o volatile combustion decreases and the peak value of fixed carbon combustion increases.After the addition of FeCl₃,the combustion range of fixed carbon expands,and the double peaks gradually melt into a single peak,and the whole transferrs to the high temperature region.3)When the hydrothermal temperature is constant,with the increase of catalyst concentration,the DTG curve of hydrothermal carbon combustion changes from double peaks to single peak,and the overall transfers to the low temperature region.4)As the heating rate increases,the ignition temperature and burnout temperature of samples increase,and the hydrothermal carbon combustion shifts to the high temperature region.5)When the hydrothermal temperature is constant,the ignition temperature and burnout temperature advance slightly after the addition of FeCl₃,and composite combustion characteristic index S_Nincreases first and then decreases.FeCl₃improves the energy quality and combustion quality of hydrothermal char,and provides theoretical basis for the application of FeCl₃in biomass thermal conversion in the future.