The general-purpose neural network processor is designed for the most neural networks algorithm and is required for variable bit length data processing ability. This paper proposes a processor that is based on SIMD (Single Instruction Multiple Data) architecture with three data bit mode: 8-bit, 16-bit and 32-bit. It can use the memory and ALU sufficiently when the bit mode changes. The processor is designed basing on 0.25–micron process technology and it can be synthesized at 50MHz with PKS of Cadence Inc. The experiment result shows that the processor can implement the neural network in highly parallel.