The rate equation analysis based on the adsorption inhibition model was performed to discuss the surface reaction process of ALP atomic layer epitaxy (ALE). The reaction process, which takes into consideration the methyl desorption and the following Al-Al reaction, well explained the experimental result that the atomic-scale surface flatness was not always retained during ALE growth. The methyl adsorbate lifetime was an important factor in surface morphology control in ALE. The shortening of the source gas feeding time within that lifetime improved the AIP surface morphology, resulting in a flat surface with atomic steps.