Mathematical model of hydrodynamic radial bearings was built up. Reynolds equation, energy equation, oil film thickness equation and viscositytemperature equation about this type of the bearing were derived. A program was compiled by Visual Fortran language, which was used to calculate oil film pressure distribution, temperature distribution and characteristic parameters about radial bearings. Effect of oilinlet temperature and rotor rotary speed on characteristic parameters of radial hydrodynamic bearings was investigated. Results indicate that corresponding position angle of such characteristic parameters as the highest temperature, the minimum thickness and the maximum pressure of oil film has a tendency to increase with the increasing of rotor rotary speed, and its position remains basically the same value with the increasing of oilinlet temperature. Accurate position of characteristic parameters calculated can provide the reference for precise measurement of characteristic parameters about hydrodynamic bearings.