In order to improve the strength of sludge, solve the problem of dredging sludge treatment in an environmentally friendly and efficient manner, biological enzymes combined with cement are used to solidify the sludge. Through the unconfined compressive strength test and direct shear test, the influence of biological enzymes on the strength of cement solidified sludge were preliminarily analyzed. The synergistic solidification mechanism was further explored by means of cation exchange capacity test (CEC),scanning electron microscope test (SEM), X-ray diffraction test (XRD), and infrared spectroscopy (FTIR). The results show that the combination of biological enzymes and cement solidification treatment has a significant improvement effect on the strength of sludge, with a maximum strength increase of 73.8%.Moreover, the amount, type and curing time of biological enzymes influenced its solidification effect, but biological enzymes do not react chemically with minerals in the soil. The combined solidification action of biological enzymes and cement is mainly achieved by promoting cation exchange in the sludge, reducing the electromotive potential of soil, improving the cementation of cement hydration products, promoting the cementation of active clay minerals, and catalytically forming the coating structure. Among all kinds of biological enzymes, Louis enzyme has the best curing effect. The unconfined compressive strength of Louis enzyme cement solidified sludge in 7 days can reach 378.8 kPa, and the cohesion and angle of internal friction can reach 307 kPa and 52.3°, which are increased to 73.8%,33.2% and 55.2% respectively higher than cement solidified sludge.