Corn stalk strength and elastic modulus are important influence factors in lodging resistance of corn. Through the mechanical experiments testing of the five varieties of corn stalk, it indicated that the stress and elastic modulus of different varieties of corn stalk strength were significantly different. The method of determining the bending strength and elastic modulus of the corn stalk was discussed. The corn stalk tester based on the simple beam model and the corn stalk elasticity tester based on the cantilever model were designed. The stretching pressure sensor, MCK—Y automatic display apparatus as the main part of electronic components, with force-loading mechanism by manual force realized digital display of bending strength and elastic modulus. The bending strength and elastic modulus of five different corn stalks were tested by using the two instruments. The comparison showed that the lodging resistance of different corn stalks was proportional to the bending strength and elastic modulus.