An algebraic analysis modelling method is introduced to analyse complicated reaction system, based on the relationship between substances studied from the atomic scope. Firstly, the feasible reaction network is identified based on the transformation of the atomic matrix. Then, the model is adjusted according to the kinetic parameters, and the most suitable grey-box model is identified, and can be applied to analyse the influence of reaction parameters (including feed, temperature, pressure and residence time) on the conversion, selectivity and yield, and provide theoretical basis for adjusting and optimizing the reaction system. The proposed method has less experimental data demand, lower kinetic parameter accuracy requirement and self-correction ability, and can be easily programmed into software. An ethylene cracking reaction is studied to illustrate its application.