A new analysis and optimization method for engine combustion was put forward in this study, which is called chemical reaction analogy method (CRAM). This method was illuminated by the similarities between the mathematical spaces of chemical reaction and engine’s combustion. Specifically, the base of the chemical reaction space are the species participating in relevant reactions, while the base of the combustion chamber are the combustion relevant geometrical and operating parameters. In addition, both spaces’ operating rules are nonlinear, and these operating rules show different sensitivities in different directions. Based on this analogy, the mathematical analysis methods of chemical reaction mechanism are introduced into the analysis and optimization of engine combustion, including sensitivity analysis, eigenvalue analysis, etc., which makes the kernel of CRAM. By this method, some typical modes of combustion chamber’s influence on performance were identified. For example, results show there are several optimization directions where NOx, soot, and fuel economy could be improved. Besides this, this paper also introduced the nondimensionalization method of fluid mechanics into the analysis to extend the availability of the method.