To improve surface planarity, a translational movement is added into the magnetorheoloigcal planarization process. To explore effects of some process parameters, including trajectory type, stroke and reciprocate velocity, on surface planarity, a set of finishing experiments are carried out. The results show that planarity is well improved when the trough reciprocates perpendicularly to the air gap. Surface planarity decreases as stoke increases but is hardly affected by reciprocate velocity. Using the magnetorheoloigcal planarization process with addition of translational movement, an ultra-smooth surface with planarity of micron order in PV is achieved on a K9 optical glass.