We establish a mathematical model for calculating stirring shaft torsion deformation and bending strength based on the existed calculation methods for the two parameters.. We show the MatLab algorithm is feasible, accurate and high-efficient, since it could solve the torsion deformation and bending strength of the stirring shaft calculation quickly and accurately. Furthermore, the algorithm and the mathematical model is convenient for calculating the bending strength of the stirring shaft and could be a reference for solving other mechanical design problems.