An LED street lamp assembly includes a central member having a first LED module fixed to a top surface thereof, a plurality of lamps attached to circumference of the central member and each having a second LED module therein, a plurality of sensors each mounted in one of the lamps and a controlling and driving circuit board received in the central member for receiving signal sent out by the sensors. If there is a goer approaches the LED street lamp assembly, the sensors are activated to send out signal to the controlling and driving circuit board to turn on the second LED modules of the lamps one by one as the goer comes closer and closer. If the goer passes by and is going away from the LED street lamp assembly, the sensors stop sending out signal to the control and driving circuit board to switch off the second LED module of the lamps one by one as the goer goes away farther and farther.