As environmental issues such as global warming continue to deteriorate and nonrenewable resources continue to be consumed, one of the primary challenges facing researchers in related fields is how to reduce the emission of soot, protect the environment and improve the efficiency of energy use. Reducing soot formation requires a fundamental understanding of the physicochemical processes from fuel to soot. However, soot formation is one of the most complex phenomena in combustion, in which both physical and chemical mechanisms exist under the influence of fuel structure, oxygen concentration, temperature, and other factors. Despite decades of active research, there are still many gaps in the understanding of soot formation. To date, there is still no unified conclusion on the growth of PAH and the incipient soot.