Abstract: This paper describes the experimental investigation on modification of the WZ-6 aeroengine into an industrial turbomachine (WZ-6G) which has been run for 1500 hours continuously as a powerplant in oil field. The fuel supply system of the engine has been reconstructed so that the natural gas is introduced through the three tubes radially inserted in the axial diffuser into a stationary jet ring, and therefrom injected into the main combustion zone. The ejection of thenatural gas from three rows of holes on the jet ring is peripherally uniform.Testing shows that the reasonable injection speed of the natural gas is 50 to 80m/s, nonuniformity coefficient of the gas temperature field at the outlet of the combustion chamber is about 0.22, Under the above conditions, the distributionof the temperature field in the combustion chamber meets the essential requirements and provides smooth combustion with the transparent light blue flame. The temperature of the flame tube wall is permissible.The main combustion chamber is actuated and ignited by the torch ignitors with natural gas as fuel.