The invention discloses an online estimation method and device for the state of charge and the state of health of a power battery and a storage medium. The online estimation method comprises the steps of 1, collecting the current, the voltage and the temperature of a single battery in real time in the charging and discharging process of the power battery, 2, in the discharging process, identifying parameters of each single battery on line through a recursive least square method with a forgetting factor, 3, estimating the terminal voltage of each single battery by using a Thevenin equivalent circuit model in the charging and discharging process, 4, estimating the SOC of each single battery by using a self-adaptive extended Kalman filtering algorithm, 5, calculating the capacity of each single battery in a charging process, and 6, calculating the battery pack charge state, the battery pack capacity and the battery pack health state, and 7, applying the calculated capacity of each single battery to the capacity parameter of each single battery in the Thevenin equivalent circuit model to realize joint estimation of the state of charge and the state of health of the battery subjected to online closed-loop feedback correction. The method can be used for accurately evaluating the inconsistency state between the battery pack monomers, and provides a basis for formulating a power battery equalization control strategy.