An acquiring method and device of residual energy of a power battery are provided. The acquiring method includes: acquiring an available capacity of a first type of cells and an available capacity of a second type of cells; determining a minimum available capacity as an available capacity of the power battery; determining available energy of the first type of cells according to the available capacity of the power battery, a current temperature, and a quantity of cells of the first type of cells; determining available energy of the second type of cells according to the available capacity of the power battery, a current temperature, and a quantity of cells of the second type of cells; and determining the sum of the available energy of the first type of cells and the available energy of the second type of cells as a quantity of residual energy of the power battery.