Abstract: SIMD (Single-Instruction-Multiple-Data) parallel architecture plays an important role in the architecture of modern processors．The instruction set of SIMD becomes the most important subset of the whole instruction set of a processor．SIMD architecture and instruction set provides the parallel processing ability for short vectors．The SIMD instruction set supports multiple data types and multiple operations．This paper described the design space of SIMD instruction set using formal method,which depicts SIMD instruction set from multiple orthogonal dimensions.Then the discussion about the design of SIMD instruction set was presented．The formal method will be beneficial to analyze and design the SIMD instruction set architecture.

Key words: SIMD,Instruction set,Design space,Formal description