Abstract: Annular hydraulic simulation is a key part of any Managed Pressure Drilling（MPD）operation. A detailed hydraulic analysis can not only be used for hydraulic parameter design of MPD, but also guide the drilling engineer real-time dealing with difficult hydrodynamic issues. According to the drilling fluid characteristics used in the MPD operation, the rheology models of drilling fluid were compared and determined. Based on experiments and theoretical analysis, taking into account the impact of bottomhole temperature and pressure on drilling fluid density and shear rate, the hydraulic simulations of MPD were conducted. The simulation results were compared with real time PWD data of the two on-site wells. The hydraulic simulation results consist well with on-site real time PWD data.