Abstract: A pet excrement collecting device capable of closing an excrement collecting bag, comprising a device body and a garbage collecting box. The garbage collecting box comprises a guide rail, a fixed pressing rod, a movable pressing rod, and at least one elastic buckle. An elastic rod is further provided in the device body, such that when the garbage collecting box is inserted into the device body, the elastic rod pushes the elastic buckle, the movable pressing rod can translate on the guide rail, and the movable pressing rod is buckled on the device body; when the garbage collecting box is extracted from the device body, the movable pressing rod can translate toward the fixed pressing rod on the guide rail; and when the garbage collecting box is taken out, the excrement collecting bag is in a fully closed state.