Abstract: In order to evaluate stalk crops with biomechanical methods, and then to provide guidance for selecting and breeding the fine varieties, the morphological characteristics (such as plant height, internode distance, moisture content and stalk dry mass) and biomechanical properties of each internode (bending strength, Young’s modulus, bending rigidity and cross sectional moment of inertia) of broomcorn, corn, soybean, millet in northern China were determined using the varieties in breeding process. The trends of biomechanical properties along with plant heights were analyzed. The reason of selecting biomechanical indices and the related experimental results were explained by elastic mechanics. The correlation analysis of biomechanical properties and morphological characteristics was conducted by Statistics Analysis System software. The results indicate that the degrees of correlation between different morphological characteristics and biomechanical properties are varied with different kind of crops. Most morphological characteristics have correlation with bending strength or with Young’s modulus. Crop morphological characteristics which are more related to these mechanical indices are obtained. The conclusions are the foundation to evaluate the lodging resistance and fine morphological characteristics of crops with biomechanical methods.