The Battery Grading Machine is mainly used for formation and capacity grading of cylindrical lithium ion batteries. Formation is first small current charging of a newly built lithium ion battery, aimed at forming a passivation layer on the surface of the negative electrode, that is, the solid electrolyte boundary film (SEI film). Capacity grading means test the capacity of the cell via charge and discharge process, and grading the cells according the capacity value. This is for balance the battery pack assembling. Battery Grading Machine is mainly composed of computer system, control software, communication interface and battery detection cabinet. The battery detection cabinet is composed of a clamp and a board body for placing the clamp, a charging constant current and voltage source, a discharging constant current source, a storage control circuit, a current sampling circuit, a voltage sampling circuit, a main control CPU, a data memory, a single-chip microcomputer program and a control panel.