Alternating current passing through alternating current light-emitting diode (AC LED) makes it not reasonable to decide luminous flux of AC LED by simply multiplying electric power and luminous efficiency. Based on alternating current effective current and light-emitting diode photoelectric characteristics, concept of AC LED equivalent luminous efficiency is introduced, and equations concerning luminous flux and luminous efficiency on equivalent luminous efficiency and the number LEDs-connected in series are established separately, then character of actual luminous flux and luminous efficiency curve are discussed. A method used to design AC LED is proposed, according to given luminous flux. Through the method theoretical AC LED luminous flux, proved less than actual value by experiment, the biggest difference is calculated.