Importance of journal bearings is not hidden to anyone with respect to many uses of them in industry. Elliptical bearings are one type of non- circular journal bearings. This type of bearing is more advantageous than circular journal bearing in terms of lower rise of temperature of oil inside it and their better performance versus vibration. In this study, energy equation has been adiabatically solved by coupling with Reynolds equation. The current essay intends to examine effect of geometric parameters of elliptical bearings on bearing functional parameters by which the optimal design of elliptical bearing can be found and at the same time the conducted works in effect of geometric parameters may be completed on functional parameters. The given results indicate that as parameter- G (non-circular parameter) is added in bearing and difference is increased among size of major axis (transverse diameter) and minor axis (conjugate diameter), the maximum diameter of fluid film and maximum rise of pressure are increase and maximum oil temperature, potential for tolerance of load and friction force are decreased. Following to increase in parameter (?) of eccentricity i.e. approaching of shaft of bearing, the maximum pressure is added and maximum oil temperature and potential for tolerance of load as well as frictional force are also increased. Keywords : Elliptical bearings, Performance Parameters, Geometric parameters, Adiabatic solution of the energy equation