Abstract: A generalized equation, which governs space charge current flow in three relativistic configurations, was derived from Poisson's equation with assumption of spacechargelimited flow. A method for solution to the equation was introduced and the characteristic of solution for the three configurations was discussed as well. It was found that the expressions of spacechargelimited flow for both the commonvertexcoaxialcircularcones and coaxial cylindrical conductors have polarity effect, which results in different distribution of space charge and electrical stress from that of planar case.