A method for estimating battery degradation is provided. In this method, a remaining capacity is obtained by looking up a device characteristic table according to a steady open circuit voltage of a battery. Besides, a constant current is provided to charge the battery, and when a terminal voltage of the battery reaches to a charging preset voltage, a constant voltage is provided to charge the battery. The transition point information at the transition from a constant current mode to a constant voltage mode, which includes a transition point estimated open circuit voltage, a transition point voltage, a transition point current and a transition point battery temperature, is analyzed based on voltage, current, temperature and capacity information measured during the charging process. A battery degradation index is calculated from the transition point information.