An alternating-current LED drive circuit, comprising a plurality of LED strings connected between an alternating-current voltage source and a ground, any one of the LED strings being correspondingly provided with a conversion switch and one or more LED light sources being connected in series in any one of the LED strings; a voltage detection unit used for detecting a voltage root mean square value of an alternating-current power supply signal in the connected alternating-current voltage source; and a switching logic control unit used for outputting, according to a voltage interval into which the voltage root mean square value detected by the voltage detection unit falls, a conversion control signal corresponding to the voltage interval to each conversion switch to corresponding to each LED string respectively control each conversion switch to perform a corresponding conversion action, the conversion action of each conversion switch enabling all LED strings to be connected in series or in parallel to adapt to the alternating-current voltage source.