The invention discloses a lithium battery state-of-charge estimation method based on high-rate discharge. The method comprises the following steps: constructing a circuit equivalent model of an energystorage lithium battery; updating parameters of the circuit equivalent model in real time by adopting a recursive least square method; establishing a state equation and an observation equation of theenergy storage lithium battery; and estimating the state of charge of the lithium battery by adopting a quadratic root volume Kalman filtering algorithm. The lithium battery state-of-charge estimation method based on high-rate discharge aims to establish an energy storage battery equivalent circuit model capable of updating parameters in real time through a recursive least square method, and accurately estimate the state-of-charge of a lithium battery in combination with a quadratic root volume Kalman filtering algorithm. According to the method, the state of charge of the lithium battery can be accurately estimated under the condition of high-rate discharge, and the method is scientific, reasonable and high in reliability.