Abstract: The heat value of coal is one of the most important coal properties that affects the operation of coal -fired boilers. The on -line analysis of heat value of coal can provide important reference for optimizing and adjusting the boiler operation in real time. The heat values of bituminous coal samples were quantitatively analyzed by laser -induced breakdown spectroscopy (LIBS). The 1 064 nm laser radiation emitted by a Q-switched Nd:YAG laser was utilized for laser ablation and plasma generation in air. The partial least square (PLS) method and the dominant factor based PLS method were used to improve the measurement accuracy of heat value of coal. In the dominant factor based PLS model, the molecular emissions of C2 and CN were utilized to build the dominant factor model. The coefficient of determination and the root-mean-square error of prediction of the PLS model were 0.94 and 1.46 MJ/kg, respectively; and those values for the dominant factor based PLS model were 0.99 and 1.18 MJ/kg, respectively. The results show that LIBS has great potential for the on-line analysis of heat value of coal.