A light-emitting-diode (LED) lamp includes a control circuit board having a control circuit and a plurality of insertion holes provided thereon; a plurality of LED units, each of which including a circuit board, a plurality of LEDs mounted on the circuit board, and terminals provided at an end of the circuit board for plugging into the insertion holes on the control circuit board to thereby electrically assemble the LED unit to the control circuit board; and a glass bulb or tube for receiving the assembled control circuit board and LED units to complete the LED lamp that can be mounted to a general lamp holder. When electricity is supplied to the LED lamp, the LEDs are driven by the control circuit to emit light for illumination. The number of LED units and of the LEDs may be adjusted according to desired illuminance.