Abstract: The numerical simulation was performed on gaseous oxygen/gaseous hydrogen shear coaxial injector as orthogonal array was applied to guide injector design.The injector combustion location was selected as the indicator of injector performance.The effect of injector mass flowrate,oxygen pressure drop,the hydrogen to oxygen velocity ratio as well as the angle of oxygen post tip on the combustion length were investigated.The range analysis and variance analysis on the results of numerical simulation indicate that the increase of injector mass flowrate make the combustion location far away from the injector faceplate,injector mass flow plays a predominated role in combustion location;and a higher velocity ratio of hydrogen to oxygen shortens the distance between the combustion location and the injector faceplate;the oxygen element drop and the angle of oxygen post tip have minimum impact on combustion location.