The mechanical stability of caprock is crucial for the safety and permanence of CO2 storage. In this study, both experimental and theoretical methods are adopted to evaluate the argillaceous (sandstones and shales) and the non-argillaceous (dolostones) caprock's mechanical and physical parameters change, during CO2 mineralized storage. These analyses enable to provide a guideline for the estimation of caprock stability. Methods: Samples of dolostones, sandstones, and shales are directly soaked in the supercritical CO2 solution (at 40 °C and 9 MPa). Firstly, variations of physical and mechanical properties are measured after CO2 soaking. Afterwards, two constitutive equations are constructed to estimate the non-argillaceous and the argillaceous caprocks' mechanical properties. From this, the mechanical-chemical coupling mechanism of CO2 mineralized storage can be characterized. Results: The experiments indicate that the compressive strength of most specimens increases at a 5 MPa confining pressure, while it decreases at a 10 MPa confining pressure. NMR analyses reveal that the porosity of argillaceous caprock showing the largest decrement after CO2 soaking. The micro-pores and meso-pores increase, but macro-pores decrease. This is possibly due to the mineralized particles filling in macro-pores, thereby enhancing the strength at low geo-stress but weakening at high geo-stress. Based on Lemaitre's principle and experimental data, the established constitutive model confirms that the porosity variation reflects the alteration of mechanical strengths. Overall, the physical and mechanical properties of argillaceous caprock are more obviously affected by CO2 mineralized storage than those of non-argillaceous caprock.