A new bending fracture principle is proposed for ear picking by simulating the process of manually breaking off corn cobs. Based on this, a new test device for corn ear picking was designed to obtain the relationship between the ear-picking rate and the rotational speed of the snapping rollers, as well as the feeding speed. A mechanical test was conducted on corn at two different harvesting stages. This proved that the tensile breaking force used in ear picking was considerably greater than that associated with bending fracture, regardless of whether it was silage or mature corn. Moreover, the feasibility of the working principle of the bending fracture was tentatively verified by a verification test. Then, ear picking could be achieved using the designed device with less damage occurring to the corn ears and straw, according to the test for corn ear picking. Finally, a range analysis showed that the highest ear-picking rate could be obtained by the test device at a snapping roller rate of 780 r/min and a feeding speed of 1.5 (m/s), with a 40° angle between the snapping rollers and conveyor. Thus, this study provides a reference for the further development of a corn harvester for silage.