The invention discloses a flexible mechanical grasping device and a grabbing method. The flexible mechanical grasping device comprises a grabbing assembly and a regulating and controlling assembly. The regulating and controlling assembly is connected to the grabbing assembly. The grabbing assembly comprises bending fingers and adsorption films. The adsorption films are arranged between the bendingfingers in pairs. The bending fingers clamp and loosen a grabbed object as the regulating and controlling assembly extracts air and sucks air. When the regulating and controlling assembly extracts air, the adsorption films are stretched to form negative pressures to cling to the grabbed object. The flexible mechanical grasping device has the beneficial effects that the flexible mechanical grasping device provides a larger application range to a clamping operation and can wrap the object self-adaptively through the adsorption films; and by designing an electromagnet, the clamping force can beimproved greatly and the flexible clamping reliability is improved.