Based on our in-house aluminum nitride (AlN) crystal growth reactor, growth characteristics and material characterization of homoepitaxial AlN growth on Al-polar AlN seeds under four different growth conditions by PVT method were investigated in detail. The results show that small tensile stresses exist in all crystals grown under four growth conditions revealed by Raman spectroscopy. When the temperature of the crucible top is 2 210 ℃, the temperature difference between the crucible bottom and top is 42 ℃, the AlN crystal is grown under a low supersaturation condition with a step-flow growth mode. And the as-grown crystal has smooth surfaces with typical AlN growth habits. The initial expansion angle of the crystal growth is larger than 40°, which indicates that quick diameter expansion is possible for AlN crystal growth. The high quality of the obtained crystals is confirmed by the rocking curves of 0002, 1012 reflections with high-resolution X-ray diffraction and Raman spectroscopy. Finally, an AlN crystal up to 45 mm to 47 mm in diameter is homoepitaxially grown successfully under the optimized growth conditions, and characterization results confirm its excellent quality and crystallinity.