Four different coals have been used to study the effects of oxygen concentration on coal combustion characteristics under different oxygen volume concentration ( 21% 、30% 、40% 、70% 、100% ) by thermo-gravimetric analysis experiments. The results show: with the oxygen concentration increases,the ignition and burnout temperatures of coal decrease and the burn-out temperature decreases faster; The ignition time brings forward,the combustion time shortens and the maximum weight-loss rate increases; The combustion of pulverized coals complies with the rule of one-rank reaction; The apparent activation energy and frequency factors of coals increase,and from brown coal to anthracite,the magnitude of apparent activation energy increases faster.