A method for reducing overactive bladder syndrome applied with an electrical stimulation device to electrically stimulate a target zone of an organism suffering from overactive bladder syndrome. The electrical stimulation device comprises at least one electrical stimulation unit. The electrical stimulation unit includes at least one first electrode and at least one second electrode. The method includes the following steps. The electrical stimulation unit is placed near the target zone. The electrical stimulation unit generates an electrical stimulation signal and the electrical stimulation signal is introduced to the target zone so as to stimulate the target zone. An electrical field is generated between the first electrode and the second electrode and covers the target zone. The strength of the electrical field ranges from 100 V/m to 1000 V/m.