Presently, the development of microparticle retention and drainage system are main embodiment in the research and exploitation of new microparticle agent.

The modification of bentonite and its microparticulate retention and drainage function to secondary fiber;

The advances of the microparticulate retention systems were introduced in the paper,especially the cationic microparticulate retention system.

The high solid bentonite suspension can be used as microparticulate retention aid together with cationic polyacrylamide.

The emphasis in this paper was put on the effects of drying temperatures,dispersing pattern and time on the particle size and viscosity of the modified montmorillonite suspension and their microparticle retention and drainage performance of the on secondary fibers.

Three different calcium montmorillonite samples were selected as model montmorilionite, and two modifiers, sodium carbonate andsodium citrate, were used to modify the montmorillonites in order to investigate the effects of morphology and modification methods on themicroparticle retention behavior of montmorillonite.

The relationship between the properties of montmorillonite and its m icroparticle retention effects on furnish together with the necessity of develop ing montmorillonite-based microparticle retention system, the factors affecting the application of it and the effects of using the microparticle system on rosi n sizing and paper strength was discussed.