The　GaN　hetero-epitaxial　layer　on　sapphire　(Al2O3)　substrate　is　studied　through　scanning　electron　acoustic　microscopy　(SEAM)　and　electron　backscattering　diffraction　(EBSD).　The　micro-area　lattice　distortion　resulting　from　the　hetero-epitaxy　mismatch　strain　at　the　interface　of　GaN　and　sapphire　is　observed　clearly,　and　the　contrast　of　the　micro-area　in　concentrated　region　affected　by　strain　is　different　significantly.　The　color　code　map　and　quality　parameter　of　the　electron　backscattering　diffraction　(EBSD)　are　used　to　analyze　the　variation　of　the　mismatch　strain,　and　the　lattice　strain　and　elastic　deformation　could　be　released　within　200　nm.