We have studied the effects of thermal annealing on surface and optical properties of AlxGa1-xN (x~0.52) heterostructure grown on sapphire substrate by metal organic chemical vapor phase epitaxy. The sample was annealed (800-960 C) in nitrogen ambient. Atomic force microscopy measurements examine on this structure. We have measured that the step flow morphology is in character within this temperature range. Moreover, surface roughness values were reduced from 1.66 nm to 0.74 nm. In addition to that the photoluminescence measurements show that luminescence intensity of AlGaN heterostructure increased with enhanced annealed temperature which is probably due to reducing interface roughness.