Abstract: Dynamic model of a whole GMAW(gas metal arc welding)system with short circuiting transfer has been built based on relationships of all relevant physical parameters.The center of the model was the sub-model about welding circuit of short circuiting transfer.Principle of minimum energy was adopted when dynamic model of liquid bridge profile was built.Dynamic behavior of the GMAW system with short circuiting transfer was simulated with the analysis of deviations. An experimental result was used to verify the model built.