An LED lamp power supply includes a power conversion module, an AC/DC control module, a dimming control module, and an auxiliary control module. The auxiliary control module further includes a sampling unit, a starting range value preset unit, a protection value preset unit, and a control unit. The sampling unit is configured to continuously collect the value of the output supply voltage. The control unit causes the dimming control module to be in a standby mode of operation when the value of the collected output supply voltage falls outside the normal stable operating voltage range and is greater than the highest voltage value. The control unit causes the dimming control module to be in a protection mode of operation when the value of the collected output supply voltage is less than or equal to the highest voltage value. The LED lamp power supply can solve the short circuit or overload of the whole circuit and the technical problems of the flashing of the LED lamp during the dimming process, thereby providing the light-emitting effect of the LED lamp to meet the needs of the user.