The 850 nm oxide confined VCSEL structure was studied and the high performance 850 nm oxide confined VCSEL were fabricated. The threshold currents of the 12 μm and 16 μm aperture are respectively 1.2 mA and 1.8 mA at 25 ℃. The slope efficiency is 0.58 mW/mA. The resistances are respectively 35 Ω and 25 Ω. The devices show good temperature characteristics and reliability. It can be used as the 1.25 Gbit/s data communication source.