A flashlight has a handle assembly and a lens cover. The handle assembly has a housing, a heat sink and en electrical unit. The housing has a front end. The heat sink is mounted in the housing and has a front end and a rear end. The electrical unit is mounted in the housing and detachably mounted on the rear end of the heat sink. The lens cover is securely mounted on the front end of the housing and has an LED element mounted securely on the heat sink. The lens cover has an LED electrically connected with the electrical unit with wires. Because the LED element and the electrical unit are separated by the heat sink, heat generated from the LED can be dissipated though the heat sink, instead of being directly conducted to the electrical unit and damaging the electrical unit.