A series of semipolar (1122) AlN epilayers have been grown on (1010) mplane sapphire substrates with the help of dual moderatetemperaturegrown (MTG) AlN interlayers by metalorganic chemical vapor deposition (MOCVD). Significant improvements in both surface morphology and crystalline quality of the semipolar (1122) AlN epilayers have been achieved with the insertion of the MTGAlN interlayers due to the formation of nanoscale patterned substratelike structure and the reduction in the basalplane stacking faults and their associated partial dislocations. The effect of the variation in the thickness of the MTGAlN interlayer ranged from 20 to 100nm was investigated in detail based on the characterization results of atomic force microscopy (AFM) and Xray diffraction. It was revealed that all the semipolar AlN epilayer samples were uniquely [1122]oriented regardless of the variation in the thickness of the MTG AlN interlayer. It was found that the most remarkable reduction in surface roughness and the most notable improvement in crystalline quality could be obtained when the thickness for the inserted dual MTGAlN interlayers was approximately 80nm.