In the paper, two kinds of nanofiltration membrane, type D and type G are applied to purify and condense maltitol. To achieve the goal of purification and concentration, membrane G plays the role of removing the multi-sugar alcohol in maltitol, and membrane D removing sorbitol as well as water. Through experiment, we conclude that when other condition parameters are fixed, permeating flux is nearly in direct proportion to operating pressure if pressure is below 1.0 MPa, however, it increases in curve as pressure increase and retaining rate becomes larger when operating pressure surpasses 1.0 MPa; permeating flux and retaining rate increase with elevating of operating pressure, and tend to be constant ultimately; the larger the concentration of material is, the less permeating flux will be, and permeating flux will drop sharply when concentration surpass 25%; when temperature increases, retaining rate decreases, while permeating flux and stolid content in filtrate increase. Through the experiment of pollution, rinse and recycle, we conclude that membrane pollution augmentation coefficient-m increases when operating pressure and material concentration increase, but decreases with accretion of cycling flux; under normal pressure, 94.6% of water-permeating flux can be retrieved after rinsed for 30 min with purging flux 140 L/h, and 98.7% can be retrieved after immersed in water for 12 h.