A 3D magnetorheological polishing device and a magnetorheological polishing fluid are provided. The 3D magnetorheological polishing device includes a container and a magnetic field generator. The container is disposed with an accommodation space to accommodate a polishing fluid and a workpiece that is to be polished. The container is disposed on the magnetic field generator and rotates synchronously with the magnetic field generator. The container and the magnetic field generator are capable of rotating in conjunction at a predetermined speed, such that the polishing efficiency is improved.