In order to obtain the influence law of structure parameters on the combustion characteristics, the numerical analysis of gaseous methane and gaseous oxygen GO₂/GCH₄ single-element splash platelet injector was investigated, and the characteristics of both chamber length and nozzle width of faceplate were studied. The chemical N-S equations were solved for the flow field, and 1-step 9-species chemical dynamic model was used to describe the reaction of methane and oxygen. The results indicate that, the characteristic velocity increases with the increase of characteristic chamber length. Under these design parameters, the corresponding value of chamber characteristic length is about 600 mm. By contrast, when the nozzle width is 0.15 mm, the mole fraction of H₂O has the biggest difference from the theoretical value; the temperatures of flow field increase at the fastest level when the nozzle width equals to 1.05 mm but increase at the slowest level when the nozzle width equals to 0.45 mm. In short, the nozzle width equals to 0.75 mm, the injector can reach the maximum combustion efficiency and the shortest combustion length compared to other cases.