<p>To explore mix proportion design of RAC with aggregates tightly packed, the dry and wet packing density of recycled coarse aggregates mixture system and recycled coarse and fine aggregates were tested, then the influence of replacement rate and particle size ratio on the packing density of particle system was explored, the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed, and the mix proportion optimization for recycled aggregate concrete with dry-wet packing model was carried out. The experimental results show that, with the increasing of recycled aggregate replacement rate or fine-grained volume ratio, the dry packing density of recycled coarse aggregates decreases gradually. With the increasing of replacement rate, the particle gradation can be optimized by increasing coarsegrained volume ratio. There is a significant effect for particle morphology parameter K and the particle size ratio on the packing density of the binary mixed system, and the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed. The maximum increase in compressive strength and tensile strength of RAC with mix proportion optimized by the dry-wet packing model are 12.94% and 11.09%, and the cementitious materials is reduced by 21.83%, then the superiority of the mix proportion optimization of RAC with the dry-wet close packing model is confirmed. The results of this paper can provide a theoretical basis for the mix proportion design of RAC.</p>