Abstract: The effect of coal, char, and volatiles (obtained from coal under different conditions) on NO reduction behavior has been investigated. The results show that original coal has an ability to reduce NO emission, and its efficiency depends on coal type and minerals within it. Atmosphere and temperature for char-making process influence the behavior of chars in reducing NO emission. Oxygen in charmaking atmosphere can change the action of chars depending on coal types. The volatiles released from high-volatile coal have a greater capacity for NO reduction, and the volatiles obtained in N2 have a greater capacity for NO reduction than that obtained in CO2, whereas the minerals in coal can break this trend. O2 in volatile-making atmosphere also affects NO reduction of volatiles depending on coal types. For Tongchuan(TC), it decreases with the increase in amount of O2 added. For Sanxie(SX), Shenmu(SM), and Jiaozuo(JZ), the best NO reduction efficiency appears when the amount of O2 added is 3%.