How to determine the fault location on-line accurately and rapidly to reduce the recovery time, when there is internal short-circuit fault in gas insulated metal-enclosed transmission line (GIL), is of most emergent importance to the safety operation of power network. With each bus-bar of GIL shell equipped with a current transformer, we can realize on-line short-circuit fault location for GIL based on current detection. Firstly, current characteristics in current transformer when a short-circuit fault occurs are discussed theoretically. Then, current distributions of current transformers under short-circuit faults of overhead line are analyzed. By using the results of current transformers equipped at both sides of fault section, we propose the on-line locating criterion for short-circuit fault of GIL. In terms of special instances, that faults cannot be located precisely which are in the first/last section of GIL, shortening the distance between two current transformers equipped at first/last section of GIL should be considered. The results of this method presented in paper are determined only by current amplitude of current transformers equipped at both sides of fault section, which is simple and reliable. Finally, Su-Tong GIL pipe gallery project is taken as an example for simulation, the conclusions of this paper are further verified.