Abstract: In order to improve the concentration of coal water slurry prepared from low-rank coal and realize the efficient and rational utilization of low-rank coal,the research progress of preparation technology of high concentration coal water slurry from low-rank coal was introduced.The research and development process,technological characteristics,concentration enrichment effect and application status of coal water slurry preparation process from single grinder preparation process to graded grinding continuous gradation slurry preparation process and discontinuous granularity gradation slurry preparation process were analyzed.Finally,problems in application and development direction of coal water slurry preparation were analyzed. The pulping process with graded grinding only has a concentration effect of about 3% compared with the conventional pulping process with single grinding mechanism.Surprisingly,the pulping process with discontinuous gradation has a concentration effect of 6% to 8%.Therefore,discontinuous gradation pulping process is the preferred technology for the preparation of high concentration coal water slurry from low-rank coal.Coal water slurry preparation technology should be further innovated and pulping raw materials such as low-rank coal and low volatile coal,industrial waste water,sludge and industrial residues should be expanded as pulping raw materials in the future,and coal water slurry combustion application technology should be developed to industrial parks and cogeneration of thermal power,to realize coal efficient,energy-saving,environmental friendly utilization.