Most static production scheduling problems are formulated in MILP ( mixed integer linear programming) or MINLP(mixed integer non-linear programming) . It is difficult to find solutions of scheduling because of its large scale and combinatorial characters. According to the features of MIP (mixed integer programming), integral variables and continuous variables are separated and the searching space is decomposed naturally into many continuous subspaces of less scale. Taking a typical batch production scheduling as a case, the analysis shows that variable-separating strategy decreases the scale of continuous searching problem greatly and makes it easy to solve, which can improve the speed and efficiency of optimization.