Abstract: As a critical technology of cemented backfill，mixing directly influences dispersion effect of Portland cement，slurry transportation property，unit consumption，and filling body's strength.However，the current study of paste backfill pays more attention to thickening of tailings，pipeline transportation and mechanical property of filling body，seldom to mixing process of slurry.With the development of paste backfill，the shortcomings of mixing procedure have been exposed gradually：Multi-scale materials' poor dispersion effect and its difficulty on homogenizing make binding material hydrated insufficiently；The inadequate capacity of one device restrains the improvement of the whole fill system；it is difficult to solve such key problems as the law of particle mixing dispersion migration and eliminate low-efficiency area.There is no excellent paste-exclusive mixer so far.Most of mixers are imitating concrete mixing equipment and technology，which couldn't fit paste backfill very well and performed poorly because of fine particle of tailings，high viscosity of slurry，high yield stress and difficult mixing dispersion.In conclusion，it is essential to develop high flow paste-exclusive mixing process and its corollary equipment.

Key words: Paste mixing, Dispersion effect, Homogenization, Dispersion migration law, Low-efficiency area