The　low-temperature　GaN　(LT-GaN)　and　high-temperature　AlN　(HT-AlN)　buffer　layers　were　grown　on　m-plane　sapphire　by　metal-organic　chemical　vapour　deposition.　The　following　semi-polar　(11-22)　GaN　thin　films　were　deposited　under　high-　and　low-pressure　growth　stages.　Anisotropy　of　(11-22)　GaN　grown　on　HT-AlN　buffer　along　two　in-planar　directions　([11-2-3]　and　[-1100])　were　clearly　suppressed,　the　maximum　variation　of　the　X-ray　rocking　curve　full　width　at　half　maximum　of　(11-22)　GaN　on　LT-GaN　buffer　was　0.2498　degrees,　that　of　(11-22)　GaN　on　HT-AlN　buffer　was　0.0488　degrees.　The　X-ray　diffraction　results　of　on-axis　and　off-axis　both　indicated　that　the　crystal　quality　of　the　epitaxial　GaN　layer　with　HT-AlN　buffer　was　obviously　improved,　and　surface　morphology　was　much　smoother.