The invention relates to a charge-discharge equalization circuit for a battery pack and a charge-discharge method. The charge-discharge equalization circuit comprises a voltage transformation circuit, N converting units and corresponding N measurement and control modules, wherein the N converting units are in cascade connection sequentially, a bypass circuit and a single battery voltage sequencing charge-discharge control method based on SOC (state of charge) are matched for use, the measurement and control modules perform online dynamic voltage equalization control in real time according to voltage or SOC difference, problems of overcharge, overdischarge, undercharge and the like in the charge-discharge processes of the battery pack are solved, and the inconsistent problem of the battery pack in the use process is effectively solved. Besides, a plurality of battery modules are not directly connected in series, but connected in series through switching circuits, and accordingly, the battery pack can be conveniently and rapidly charged and discharged; meanwhile, later work such as maintenance, overhauling and the like of the equalization part of the circuit is more convenient.