A new InP MESFET structure both with a gate structure of stacked metal and with a active channel of stacked layer is proposed. The gate metals are constituted by a double metal structure, Pt/Al. It improves the barrier height and reduces the reverse leakage current in the MFSFET. This is due to the formation of Al2O3, and becoming a Pt/Al/Al2O3/InP, metal-insulating-semiconductor structure in the gate region of the transistor. The conductive channel is constituted by a stack-layered structure, a n-InP layer and an i-InP layer. A transfer characteristics of excellent pitch off, and transconductance of 93 mS/mm is derived. It also shows a negative differential resistance effect on the MESFET. The illumination and temperature effect of the transistor are brought into discussed.