In this paper, by applying Kronecker product and vectorization operator, we extend two mathematical equivalent forms of the conjugate residual squared (CRS) method to solve the periodic Sylvester matrix equationWe give some numerical examples to compare the accuracy and efficiency of the matrix CRS iterative methods with other methods in the literature. Numerical results validate that the proposed methods are superior to some existing methods and that equivalent mathematical methods can show different numerical performance.where the coefficient matrices A j , B j , C j , D j , E j ∈ R m×m and the solutions X j ∈ R m×m are periodic with period λ, that is, A j+λ = A j , B j+λ = B j , C j+λ = C j , D j+λ = D j , E j+λ = E j , and X j+λ = X j . The periodic Sylvester matrix equation (1.1) attracts considerable attention because it comes from a variety of fields of control theory and applied mathematics [1][2][3][4][5][6][7][8][9][10][11][12].In recent years, many efficient iterative methods have been proposed to solve the periodic Sylvester matrix equation (1.1). For example, Hajarian [13,14] developed the conjugate gradient squared (CGS), biconjugate gradient stabilized (BiCGSTAB) and biconjugate residual methods for solving the periodic Sylvester matrix equation (1.1). Lv and Zhang [15] proposed a new kind of iterative algorithm for constructing the least square solution for the periodic Sylvester matrix equation. Hajarian [16] studied the biconjugate A-orthogonal residual and conjugate A-orthogonal residual squared (CORS) methods for solving coupled periodic Sylvester matrix equation, and so forth; see [17-28] and the references therein.As we know, by applying Kronecker product and vectorization operator, some iterative algorithms for solving linear system Ax = b can be extended to solve linear matrix equa-