This paper is intended to provide a method for the transformation of multi-vehicle flow networks equivalently into single-vehicle flow ones. As we know, the multi-vehicle flow problems often turn up in our practice. Using this method,we can solve the problems easily and the efficiency of algorithms for solving multi-vehicle flow problems can be increased considerably. The general probhms as well as two-vehich problems are dealt with in detail. Finally, a sample problem with two-vehicle is given.