Abstract: Although microbially induced carbonate precipitation(MICP)technology has been widely applied in soil reinforcement and seepage control,only limited research has explored its use in rock mass reinforcement and sealing projects. In particular,few studies have considered how the contact area within rock joints influences the permeability reduction achieved through MICP treatment. To address this gap,unmated granite rock joint specimens obtained from repeated direct shear tests were used as prototypes. Artificial rock joint specimens with varying initial contact area ratios were fabricated by combining laser scanning of surface morphology with 3D printing technology. Laboratory MICP experiments were then conducted on these specimens to examine the effect of contact area on permeability reduction. The experimental results reveal that the initial contact area governs the formation of the initial calcium carbonate deposition zone during the MICP sealing process,thereby influencing the final distribution of calcium carbonate. Notably,a distinct zone devoid of carbonate deposition was observed. Furthermore,the transmissivity of the rock joints exhibited a two-stage decline with MICP injection cycles: a rapid reduction after the first cycle,followed by a gradual decrease in subsequent cycles,eventually approaching zero. Based on the experimental data,an empirical linear relationship was established among transmissivity,final calcium carbonate diffusion area ratio,and initial contact area ratio. This expression can be used to preliminarily predict transmissivity and the final distribution of calcium carbonate during MICP-based sealing of rock joints.