Mechanism　of　tin　whisker　growth　on　the　surface　of　the　oxidized　ErSn3　phase　was　investigated　by　analyzing　FIB　images　of　the　oxidized　ErSn3　phase.　The　results　indicate　that　many　＂rapid　oxidation　channels＂　and　＂oxidation　zones＂　were　formed　inside　the　ErSn3　phase　after　its　inhomogenous　oxidation.　Because　two　＂oxidation　zones＂,　which　were　connected　with　＂rapid　oxidation　channel＂,　were　formed　below　and　around　the　root　of　whisker,　respectively.　Thus,　a　＂double　compressive　stress　zones＂　model　for　tin　whisker　growth　was　proposed　as　follows:　two　compressive　stress　zones　are　required　for　tin　whisker　growth,　the　＂low　compressive　stress　zone＂　that　located　at　the　root　of　whisker　provides　driving　force　for　whisker　formation　and　the　＂high　compressive　stress　zone＂　provides　tin　atoms　for　whisker　growth.