Abstract: Model transformation is a key challenge in large-scale model driven engineering.It costs too much to write model transformation rules manually，at the same time，correctness can’t be ensured.A model comparison algorithm is designed to generate transformation rules automatically based on edit distance.This algorithm can deal with UML class diagrams，state diagrams and activity diagrams.It can also check the move and copy operations between models to generate minimum transformation sequences，which can raise model transformation efficiency.By experimental verification，it is feasible and fairly efficient to generate model transformation rules automatically based on this algorithm.