The invention discloses an ultra-precision flexible chemical mechanical polishing device and method for a micro bearing core element. The core element comprises an inner ferrule, a retainer, a rollingbody and an outer ferrule. The polishing device comprises an element rotation module, an outer ferrule steering module, an element clamping module, a polishing liquid pool rotation module and a support. The element clamping module provides an inner ferrule clamp, a retainer clamp, a rolling body clamp and an outer ferrule clamp in a targeted manner. The polishing method comprises the steps of installing and debugging the polishing device, preparing flexible chemical mechanical polishing liquid, setting polishing process parameters, measuring the surface quality and conducting feedback. The flexible chemical mechanical polishing liquid comprises non-Newtonian fluid, 0.01-40 wt% of grinding particles, 0-10 wt% of an oxidizing agent, 0-10 wt% of a metal complexing agent, 0-5 wt% of a metal corrosion inhibitor and the balance water, and the pH value is 2.0 to 10.0. According to the ultra-precision flexible chemical mechanical polishing device and method, by optimizing the synergistic effect of the chemical reaction and the mechanical force of the force rheological effect, ultra-precision low-damage machining and complex curved surface shape-preserving machining of the surface of the core element can be achieved, and the device and method are green and environment-friendly.