The invention belonging to the field of batteries provides an equalization method for a battery pack. The equalization method includes: first charging is carried out; a first voltage of each single battery is detected; second charging is carried out; a second voltage of each single battery is detected; a real voltage of each single battery is calculated and the real voltages are compared and a difference between the maximum value and the minimum value of the real voltages is determined; whether the difference value is greater than a starting voltage threshold value is determined; if so, whether equalization is first equalization is determined; if so, an average value is calculated; a first number with the real voltages less than an average value and a second number with the real voltages larger than an average value are calculated; whether the first number is smaller than the second number is determined; if so, an active equalization mode is started; and if not, passive equalization mode is started; and if the equalization is not first equalization, the last equalization mode is read and started.