Abstract: To address the common problems of underburning and overburning of limestone particles during the decomposition process, as well as the difficulty of accurately describing the calcination process of lime kilns via conventional numerical simulation methods, this paper proposes a dual coupling numerical simulation method of shrinking core and porous medium. By coupling the user-defined function (UDF), this method breaks through the limitation of constant material moving velocity, realizes accurate coupling between gas-phase combustion and solid-phase movement, and successfully controls the simulation error within 10%. Under ideal conditions of pure spherical limestone with uniform particle size, the regulation mechanisms of material input rate, particle size, and heat load on the decomposition rate and yield of limestone were systematically investigated using single-factor analysis. The results show that the material feed rate is negatively correlated with the decomposition rate, and the maximum yield is obtained at the feed rate of 21.5 t/h; the particle size regulates the heat and mass transfer efficiency by controlling the bed permeability, and the 20 mm particles achieve the highest heat and mass transfer efficiency; increasing the heat load can significantly improve the decomposition rate, while there exists an over-burning risk at 1.4 times the reference heat load. Through the analysis of influencing factors in the production process of TGS lime kilns, this study can provide theoretical support for the process optimization and operation regulation of lime kilns.