Abstract: Hyperbolic tangent function (Tanh) is often used as an activation function in neural networks, but its non-linear character makes it difficult to be realized by hardware circuit directly. In order to implement the Tanh function quickly and efficiently, the DCORDIC(Differential Coordinate Rotation Digital Computer) algorithm is proposed to implement the hyperbolic sine/cosine function and division operation in different modes, and a selection module is added to expand the range of input data. The final design implementation of the tanh computation core has a very long pipeline with a computational error of 2^-8. Compared with the existing hardware implementation methods, the proposed implementation method has smaller error, higher computing speed and greater throughput.