Direct wafer bonding between InP and SOI wafers was carried out with Al2O3 as the intermediate layer. The Al2O3 intermediate layer was formed on the surface of SOI wafer through atomic layer deposition, followed by surface activation of the wafer with oxygen plasma treatment. Atomic force microscope and contact angle tests show that oxygen plasma treatment makes the surface of wafer suitable for direct wafer bonding. Test results of transmission electron microscope and energy-dispersive X-ray spectroscopy confirm the reliable wafer bonding between InP and SOI wafers using Al2O3 as the intermediate layer.