Cement (sand) slurry in the concrete plays a dual role of gelation and lubrication, its dosage with concrete increase with the increase of fluidity requirements, the existing research shows that slurry can lead to volume stability of concrete problems and low degree of green environmental protection, but the aggregate gradation on the effect of reasonable dosage of slurry in the concrete research is still rare. The influence of coarse aggregate grading and mortar rheological features on the mortar coating thickness and mortar coating content of coarse aggregate is studied by adjusting the mortar content under the condition of equal slump-flow of concrete, which coarse aggregate has a fixed amount and relative less bulk voids. The mortar coating thickness increases monotonically with the increase of the geometric average particle size of coarse aggregate, mortar coating content shows a trend of first decreasing and then increasing, while a minimum mortar coating content occurs around the optimal geometric average particle size. It has also been proved that larger mortar coating thickness and mortar coating content are required with higher fluidity, but the smaller the optimal geometric mean particle size. The mortar coating thickness and mortar coating content increase with the increase of mortar yield stress and plastic viscosity under fixed particle size grading of coarse aggregate.