The history and current situation of magnetorheological finishing (MRF) at home and abroad are presented. The principle, characteristics and merits of MRF are introduced. Recent investigations of MRF at Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) are described in detail, and several key techniques of MRF are resolved. Our research findings include: A new-style magnetorheological (MR) polishing fluid is prepared, and the rheology and polishing power of this MR polishing fluid are improved evidently; dwell time algorithm of MRF based on matrix algebra is studied; in order to increase the area of removal function (polishing spot), improve the material removal rate, and polish large aspheric mirror, a new MRF concept, named Belt-MRF, is presented.