The present invention discloses an optical fiber connection protecting box for connecting the tail fiber of the common indoor optical fiber and the leather-wire optical fiber. The optical fiber connection protecting box comprises the following components: a substrate which includes a locating part of the tail fiber fixing mechanism and a locating part of the leather-wire optical fiber fixing mechanism which are arranged spacing with each other for a certain distance; a bare fiber connection device which connects the common indoor optical fiber and the bare fiber in the leather-wire optical fiber; a tail wire fixing device which is fixed on the locating part of the tail fiber fixing mechanism of the substrate and connects the tail fiber in the common indoor optical fiber, wherein the bare fiber of the tail fiber traverses the tail fiber fixing device with a prearranged length and the bare fiber connecting device executes connection; and a leather-wire fixing mechanism which is fixed onthe locating part of the skin-wire optical fiber fixing mechanism of the substrate and is connected with the leather-wire optical fiber, and the bare fiber of the leather-wire optical fiber traversesthe leather-wire optical fiber fixing mechanism with a prearranged length and the bare fiber connecting mechanism executes the connection to the bare fiber of the tail fiber. The invention can effectively connect the leather-wire optical fiber with the tail fiber of the common indoor optical fiber and directly fixes the tail fiber through a reinforcing piece in the tail fiber. The leather-wire optical fiber and the tail fiber can be firmly and stably connected, and the fiber core wherein can be effectively protected.