Abstract: Compiler backend is the implementations in a compiler for a specific target machine．Different instruction set architecture needs different implementations of compiler backend．Targeting for the architecture and instruction set of the Vector Processing Unit (VPU) in FT processor,we implemented the compiler backend based on GCC．And we made it possible for GCC to correctly compile the intrinsic functions oriented to the SIMD instructions in FT-VPU．In this paper,from the machine description for the four-way double precision SIMD instructions,we concluded the backend implementations in GCC for FT-VPU．Our work is valuable reference to implement a compiler backend for a specific target machine based on GCC.