A three-dimensional (3D) glasses and a method for operating the same are provided. The 3D glasses includes a first lens, a second lens, an infrared receiver and a control unit. The infrared receiver receives an infrared signal to output a digital control signal. The control unit is coupled to the infrared receiver. The control unit controls a first state of the first lens and a second state of the second lens according to a first pulse of the digital control signal, where at least one of the first state and the second state is an OFF state.