Based on the gasoline engine with 100mm cylinder diameter, the model is established by GT-POWER software, and through many times of simulation calculations, the reliability of the model is tested and verified. A comparative study is carried on the curve diagram of the gasoline engine detonation indexes changed with the related changes, when the cylinder diameter, the compression ratio, ignition advanced angle, rotational speed and the concentration of the mixed gas are changed. The analysis is that the engine detonation indexes are increased with the cylinder diameter rising. Also they are increased with the increase of the compression ratio and when the compression ratio is more than 9.5 , it is sharply rising. It is decreased with the rotational speed increase. Especially at a low speed, the detonation index is sharply decreased with the rotational speed rising. It is reduced with ignition advance angle decreasing. Thick or thin mixed gasoline engine detonation indexes are all reduced and the detonation tendency is also decreased.