Valence electron structure has an intrinsical influence on the physical properties of material. On the basis of empirical electron theory of solids and molecules, combining with dynamic mechanical process of calculating steel, we constructe a new model for calculating static and dynamic strengths of steel. The static (dynamic) strengths of multi-composition steel, predicted by the proposed model, accord well with the experimental values. It is the first time to introduce the valence electron structure into the model for predicting dynamic properties.