Abstract: SBOX is the most time consuming part in block cipher SM4algorithm,so it's of great importance to construct a S box of high performance.In order to reduce latency of encryption algorithms in SM4,We introduce the N-dimensional hypercube method to construct SBOX,the delay reduced six percent and the area reduced seventeen percent Compared with the traditional S box using look-up table method.what's more,this method is portable that it can apply to SBOX transformations of other algorithms.