The present invention provides a room door lock anti-opening device comprising an execution portion, a control portion, a communication portion and a power supply portion. The control portion establishes mutual recognition with an external intelligent device via the communication portion so as to form a binding relationship, and receives an operation instruction of the pre-bound external intelligent device. When a lock bolt completely stretches out, the execution portion is driven by mechanical force to stay at a lock bolt returning route, and a room door cannot be opened by a key under the state. When the control portion receives an unlocking permitting instruction given by the pre-bound external intelligent device, the control portion notifies the execution portion to trigger power in areverse direction of the mechanical force and return to the position beyond the lock bolt moving route, the execution portion returning action maintains a preset duration, and the room door can be opened by the key under the state. According to the room door lock anti-opening device, the mechanical key and the external intelligent device are cooperated to form a dual-locking mechanism, and the antitheft capability of an existing room door lock is improved.