The adsorption and desorption behavior of adatoms on AlN(0001) surface with steps and kinks during metal organic vapor phase epitaxy (MOVPE) is systematically investigated by means of ab initio calculations. The calculations demonstrate that the adsorption behavior of Al and N adatom near the steps and kinks depends on the surface reconstruction. The Al adatom is preferentially incorporated at the kink, while the N adatom can be incorporated not only at the kink but also in the terrace regions. The calculated results give insights to understand the step-flow growth during AlN MOVPE.