The invention discloses a rotary type graphene slurry preparation system and a preparation method. The preparation system comprises a stirring device, a sand mill and a ball mill, wherein a discharging opening of the stirring device is communicated with a feeding opening of the sand mill; a discharging opening of the sand mill is communicated with a feeding opening of the ball mill; the stirring device comprises a stirring cabin, a driving assembly and a stirring assembly; the stirring assembly is arranged in the stirring cabin; the driving assembly provides power for the stirring assembly; the stirring assembly comprises a stirring shaft I, a stirring shaft II and stirring blades. Compared with the prior art, the preparation system and the preparation method have the beneficial effects that the stirring blades rotate on a longitudinal plane when the stirring shaft II rotates, and the stirring blades rotate and stir by 360 degrees by taking the longitudinal shaft of the stirring shaft I as a rotating shaft when the stirring shaft I rotates, so that the stirring direction is more comprehensive, the stirring is conducted completely, and power raw materials and solvents are mixed uniformly.