The invention discloses an intelligent online monitoring device and method for a circuit breaker operating mechanism. The intelligent online monitoring device comprises two displacement sensors, a baffle plate, a supporting plate, a hinge pin, a spring, a pull rod, an LC oscillation circuit, a shaping circuit and a CPU (Central Processing Unit), and is characterized in that the positions of the two displacement sensors correspond to the position of the supporting plate and the position of the end part of the baffle plate at a compression state of the spring, connecting lines at two ends of a detecting coil of each displacement sensor go through an iron core and are led to the LC oscillation circuit, the output of the LC oscillation circuit is connected with the shaping circuit, and the output of the shaping circuit is connected with a high-speed counting interface of the CPU. The frequency of the LC oscillation circuit is calculated through a count value of a high-speed counter within a set timing time, so that inductance of the detecting coil is acquired, thus the distance between each displacement sensor and the baffle plate is calculated, and deformation of the supporting plate and the baffle plate after energy storage of the spring is calculated. The intelligent online monitoring device acquires a static stress value of the operating mechanism by adopting the non-contact displacement sensors, and is free of mechanical abrasion and long in service life.