Abstract: This paper describes how to choose and modify the WZ 5 gas turbine for steam injec tion testing and how to evaluate testing parameters and programmes.Testing results indicate that when the steam is injected 3 6t/h into the WZ 5 gas turbine,its power output and thermal efficiency increase 40% and 25% respectively.Moreover,the steam injection does not dete riorate the exit temperature profile in the turbine,which ensures a long term reliability of operation for the engine.