An LED illumination system includes a DC power supply, at least two LED illumination lamp sets and at least two power circuits corresponding to the LED illumination lamp sets. The DC power supply provides sufficient electric power for the LED illumination lamp sets and is connected to the LED illumination lamp sets via the power circuits. The invention supplies electric power required by the LED illumination lamp sets via a single DC power supply without an extra DC power supply, hence the cost is lower. Moreover, the DC power supply is located remote from the LED illumination lamp sets, hence high temperature generated by the DC power supply does not affect lighting and lifespan of the LED illumination lamp sets. The hazard of electric shock by inadvertently touching the AC power source while replacing lamps in the LED illumination lamp sets can also be avoided to improve safety.