The primary purpcse of this paper is to analyse the lubrication mechanism of the spherical surface hydrodynamic sliding bearing. A two-dimensional flow Reynold's equation and an oil film thinckness equation, which take radial and axial dimensionaless eccentricity into account, are established by a spherical coordinate system. Thcse two equations are simultaneously solyed by computer.Finally,a curve of oil pressure distribution is obtained and its feature of carrying capacity is analysed and calculated.