Lithium battery charging and discharging control method and power supply system

The invention is applicable to the technical field of electric power supply, and provides a lithium battery charging and discharging control method and a power supply system. The lithium battery charging and discharging control method comprises the steps of acquiring the current voltage of a lithium battery; if the current voltage is less than a preset first charging voltage threshold, charging the lithium battery with preset first constant current; if the current voltage is greater than or equal to a preset second charging voltage threshold, charging the lithium battery with preset second constant current; and if the current voltage is greater than or equal to a preset third charging voltage threshold, stopping charging the lithium battery. According to the lithium battery charging and discharging control method and power supply system provided by the embodiment of the invention, charging control is carried out on the lithium battery in stages through controlling the size of the charging current, thereby avo