The utility model provides an independent smoke-sensing fire detector. The detector comprises an upper cover, a lower cover, a pedestal and a core assembly. The upper cover and the lower cover are engaged to form an installation space, in which is installed the core assembly. The lower cover is provided with snap hooks at the bottom, and the pedestal is provided with snap hook pairing portions corresponding to the snap hooks. During installation, the lower cover rotates with respect to the pedestal, and the snap hooks are engaged with the corresponding snap hook pairing portions so that the lower cover and the pedestal are connected. The lower cover is also provided with a battery slot for installing a battery. An elastic column including a protruding portion and a contacting portion is arranged on one side of the battery slot. The contacting portion extends into the battery slot. The pedestal is provided with a notch engaged with the protruding portion. When the battery is installed into the battery slot, the battery presses the contacting portion, and the protruding portion is disengaged with the notch. The detector can prevent forgetting to install the battery during installation, so that hidden troubles of safety are eliminated and the safety performance is improved.