Aluminum gallium indium nitride（AlGaInN） quaternary epilayers were prepared by metalorganic chemical vapor deposition （MOCVD） on c-plane sapphire （α-Al2O3） substrates. Three samples were grown under different temperatures of 800 ℃，850 ℃ and 900 ℃. It is found that the In composition monotonically decreases with the increasing growth temperature，while the Al composition is nearly invariable. The V-pits appeared when the growth temperature increases to 850 ℃, and the size and density of V-pits drastically decrease and the nucleation of V-pits is passivated when the growth temperature rises to 900 ℃ due to the desorption enhancement of segregated In atoms.