The invention discloses a method for preparing high-concentration coal water slurry by means of fine crushing and little grinding. The method includes steps of (1), mixing and stirring fine coal powder, water and additives with one another in mixing and stirring tanks to obtain slurry; (2), finely grinding the slurry by the aid of wet processes to obtain fine slurry A, feeding the fine slurry A back into the mixing and stirring tanks, mixing and stirring the fine slurry A, the fine coal powder, the water and the additives with one another to obtain finished coal water slurry, diluting a part of the finished coal water slurry by water and then finely grinding the diluted finished coal water slurry by the aid of wet processes to obtain fine slurry B, feeding the fine slurry B back into the mixing and stirring tanks in a circulation manner and carrying out mixing and stirring steps. The method has the advantages that the high-concentration coal water slurry is prepared by means of fine crushing and little grinding, the conventional single-rod/ball mill ore grinding slurry production can be replaced, slurry production energy consumption can be saved by 40-65%, accordingly, the slurry production cost can be obviously reduced, and the high-concentration coal water slurry is high in concentration, low in viscosity and good in flowability and stability.