ZnO　thin　films　were　prepared　on　Na-Ca-Si　glass　substrate　(microscope　slides)　by　Sol-Gel　process,　and　the　mechanism　of　ZnO　thin　film　prepared　by　Sol-Gel　technique　was　discussed　by　DTA　for　the　first　time.　The　thin　film　was　analyzed　by　SEM,　XRD　and　UVS.　The　results　showed　that　the　thin　film　with　strongly　preferred　orientation　of　C-axis　perpendicular　to　the　substrate　surface　was　the　crystalline　phase　of　hexagonal　wurtzite.　Its　surface　was　homogenous,　dense　and　crack-free.　The　thin　film　was　composed　of　plentiful　asteroid　crystal,　the　size　of　which　is　10　nmsimilar　to30　nm　approximately.　The　transmittance　of　the　thin　film　in　visible　region　was　above　90%.　The　results　also　showed　that　the　thickness　of　single　dip-coating　was　about　75　nm.　The　wavelength　414　nm　emission　was　observed　in　ZnO　thin　film,　being　excited　with　313　nm　light　beam.