Abstract: The carbonization resistance is a serious problems for the engineering residue limits its application in practical engineering. Therefore, this study aims to address this issue by enhancing the carbonation resistance of the stabilized soil, expanding its application scope. In this paper, the mechanical properties and microstructure of solidified residual soil were studied with metakaolin as the main material of curing agent. Further, the carbonization resistance and microstructure of solidified residual soil were studied by soaking and activating the residual soil with nano-SiO₂. The results show that with the extension of carbonization time, the carbonization time less than 6 h has a certain improvement effect on the solidified soil mechanics, and the carbonization time has a deterioration effect on the strength for long time. The compressive strength of 28 d after carbonization for 24h is 11.2 MPa, which is reduced 32.5%, and the bending strength is 2.19 MPa, which is reduced by 34%. In the early stage (within 6 h of carbonization), 2% nano-SiO₂ has a significant improvement effect on the deterioration of mechanical properties, improving the early strength of solidified soil in the early stage. Microscopic analysis found that the degradation effect of carbonization on mechanical properties of solidified soil was due to the decomposition of a large number of N-A-S-H gels, and the introduction of SiO₂ had a certain microscopic improvement effect on the degradation caused by carbonization, making the internal structure dense of the system. This study has the existing application value and theoretical significance. This research has significant practical value and theoretical guiding significance, providing new ideas and methods for the efficient utilization of construction waste.