Aspects for matrix multiplication in neural network are described herein. The aspects may include a controller unit configured to receive a matrix-multiply-matrix (MM) instruction that includes a first starting address of a first matrix, a first size of the first matrix, a second starting address of a second matrix, and a second size of the second matrix; multiple computation modules configured to respectively multiply, in response to the MM instruction, row vectors of the first matrix with column vectors of the second matrix to generate one or more result elements; and an interconnection unit configured to combine the result elements to generate one or more row vectors of a result matrix.