In the study, humic-like substances (HULIS) in smoke PM_2.5 emitted from the combustion of biomass materials and fossil fuels are studied. The results indicate that both biomass burning and coal combustion are important primary sources of atmospheric HULIS. Moreover, the primary HULIS and atmospheric HULIS are similar in many properties, but some distinct features are also apparent. These results are helpful to understand the contribution and chemical nature of HULIS in combustion emissions.