The present invention discloses a method for rapidly estimating for a remaining capacity of a battery, comprising performing a constant current charge to the battery in a first period, instantly capturing a voltage/temperature of the battery in a frequency, and generating a voltage-time graph; after leaving the battery along for a second period, instantly capturing the voltage/temperature of the battery in the frequency; calculating a voltage rising rate during the first period; calculating a voltage drop rate during a leaving-along period; calculating a critical sample time; applying the critical sample time, and comparing the voltage-time graph measured in the first period, to obtain a critical sampling voltage; calculating a voltage difference slope; calculating a charging time, which is consumed by charging the battery from a lower-bound voltage to an upper-bound voltage with the constant current; calculating a compensation ratio value; and calculating the remaining capacity of the battery.