This paper presents a reconfigurable back-propagation neural network (BPNN) processor hardware architecture as well as doing non-linear function approximation. The purpose of modulation is to make the network more flexible for different applications. The neural network architecture is written in the from of instructions into the chip through the input / output ports (I / O) to reconfigure the neural network architecture. In the implementation of Network Computing, the multi-processor computing architecture is applied in order to reach the parallel computing capacity, and to reduce the time consumed for the learning cycle of back-propagation neural network. The BPNN chip is synthesized by UMC 90nm cell library, and is worked at 50 MHz. The area of the BPNN chip is about 2.2x2.2 mm2 .