Abstract: To solve the problem of difficult prediction of fluid density and rheology during the managed pressure cementing (MPC) injection stage, the measurement experiments of fluid density and rheology were designed, and the rheological model was optimized based on the experimental results. Then, a temperature-pressure coupling model was established considering the difference in fluid properties, and a segmented prediction method for fluid density and rheology was proposed. Finally, the Well X in northern Sichuan was taken as an example, and the simulation results show that the segmented method can describe the rheology of the fluid more accurately by taking the Herschel-Buckley model, the four-parameter model, and other rheological models as the preferred objects. During the MPC injection stage, the conventional calculation method can make the wellhead back pressure value low, which will greatly increase the risk of formation gas invasion. Meanwhile, the annulus temperature field predicted by different methods has little difference. The coupling effect of temperature and pressure has a great influence on the density and rheology of fluid and their variation law, which will also greatly affect the design of the annular slurry column structure and cementing effect. The research results provide a theoretical basis for the design and operation of MPC.