Abstract: The present work aims at industrial modification of WZ-5 aeroengine to runon medium BTU gas fuel which is a typical waste gas come from chemical fertilizer production. The medium BTU gas fuel contains 50% of H₂,20% of CH4 and H₂, and its low heating value is 3000kcal/Nm³. Four injectors have been designed and tested in the combustor of the engine. Three of them have quite good performance, the injector with slat-shape opening at its end is unsuitable because of unacceptable temperature distribution at the exit of the combustor. It is also shown that there is the potentiality for the modified combustor to be improved as the medium BTU gas fuel contains a certain amount of H₂.