GaAs　and　GaN　wafer　pairs　are　successfully　bonded　based　on　the　hydrophilic　surface　treatment.　The　bonding　is　carried　out　at　500°C　in　N2　atmosphere　for　10　min.　It　is　found　that　a　large　fraction　of　the　interface　area　is　well　bonded.　SEM　results　indicate　that　there　is　no　air　gap　at　the　bonding　interface.　PL　measurements　indicate　that　the　crystal　structure　is　slightly　affected　by　the　wafer　bonding　process.　Visible　light　transmission　measurements　indicate　that　the　GaAs/GaN　bonded　interface　is　translucent.　Success　in　GaAs/GaN　direct　wafer　bonding　has　great　implications　for　the　integration　of　GaAs　and　GaN　semiconductor　materials.