An AC two-wire LED high voltage lamp string with synchronous dimming and color adjustment comprises a high voltage controller and a lamp string group, wherein the high voltage controller comprises a control box, and a first power supply module, a switch control circuit and a first microcontrol unit which are arranged in the control box and connected in sequence; the first power supply module is connected with the switch control circuit and the first microcontrol unit; a second microcontrol unit. The present invention modulates and encodes a high voltage sine wave using the switch control circuit at the controller end and demodulates the sine wave at a bulb end to realize the functions of color change timing, flashing, timing and light control of lamp strings. The lamp strings can be used individually or connected in series and in parallel for use, to satisfy different needs of consumers.