For complex composition of reclaimed asphalt concrete(RAP) particles to accurately control the gradation of recycled asphalt concrete, based on grey system theory, putting deviation value of void ratio in RAP porous asphalt concrete as system behavior and percentage of virtual coefficient(Kc) in synthetic screening as relevant factor behavior to analyze grey correlation between the two behaviors, this work figures out grey correlation degree sequence which represents recycled asphalt concrete gradation accuracy and RAP particles relations. Results indicate that RAP particles with different particle size range have different compositions, and impact on the gradation of the recycled asphalt concrete is more obvious with the larger RAP particle size. Through comparative analysis of correlation, a virtual screening curve is simulated，which is close to real particles state of RAP. And this virtual screening curve can accurately control the gradation of recycled asphalt concrete.