Microbial induced calcium carbonate precipitation (MICP) cemented remolded mudstone samples were prepared by injecting one-time bacteria solution with different concentrations (0, 0.3, 0.5, 0.7 mol/L) of nutrient salt treatment. Based on the results of direct shear test, calcium carbonate pickling and scanning electron microscopy (SEM), the effects of nutrient concentration on the mechanical properties, calcium carbonate content and microstructure of the cemented samples were analyzed. The results show that under the same reaction conditions (same time, volume), the shear strength increase at first and then decrease with the increase of nutrient concentration. When the nutrient salt concentration reaches 0.5 mol/L, the shear strength reaches the largest value. At this time, the cohesive force and internal friction angle of the sample are 15.5 kPa and 18.83°, respectively. The content of calcium carbonate increase with nutrient concentration. When the concentration of nutrient salt reaches 0.7 mol/L, the average calcium carbonate content of the sample increases less. The uniformity of calcium carbonate crystal distribution changes in a convex shape with the increase of nutrient salt concentration from low to high. The strength of the cemented sample depends on the amount of CaCO₃ crystals formed and their distribution. The produced calcite-type calcium carbonate crystals are mainly deposited at the contact position of the particles to form accumulated crystals or filled in the pores to form a "bonding bridge", which produces a cementation effect and enhances the mechanical properties of the sample.