Frost　formation　is　a　common　phenomenon　under　cryogenic　conditions.　Without　effective　control,　frost　deposition　may　result　in　serious　malfunction　of　cryogenic　equipment　and　systems.　In　this　paper,　an　experimental　study　on　the　initial　period　of　frost　deposition,　the　crystal　morphology　and　its　variation　with　time　of　frost　ice　are　carried　out　of　frost　formation　on　a　vertical　plate　by　microphotographics.　The　phase　change,　the　initiation　of　frost　formation　and　the　different　shapes　of　frost　crystal　at　various　time　stages　are　described.　It　is　proved　from　the　present　study　that　the　main　factors　that　affect　frost　formation　in　natural　convection　are　plate　temperature,　air　humidity　and　air　temperature.　In　order　to　explain　the　frost　thickness　difference　under　various　conditions,　a　frost　thickness　growth　driving　force　is　defined　and　compared　with　the　experimental　results.　Hydrophobic　surfaces　are　used　to　release　frost　formation　on　cold　surfaces　and　the　results　show　that　these　surfaces　can　retard　the　formation　and　growth　of　frost　significantly.