In order to improve coarse aggregate system and further improve the performance of recycled concrete, two series of recycled concrete were prepared with 64% and 36% replacement ratio of recycled coarse aggregate without changing natural coarse aggregate gradation. The effects of natural/recycled coarse aggregates with different particle sizes (［5,10) mm, ［10,20) mm, ［20,31.5］ mm) on workability, mechanical properties and durability of concrete in mixed coarse aggregate system were investigated. The results show that when the total replacement rate of recycled coarse aggregate is constant, with the increase of recycled coarse aggregate size, the slump/slump flow of recycled concrete increases continuously, the compressive strength, flexural strength and elastic modulus basically increase, and the electric flux and carbonation depth gradually decrease. Under the condition of high replacement ratio of recycled coarse aggregate, increasing the proportion of 20 mm to 31.5 mm recycled coarse aggregate is more conducive to improving the mechanical properties and durability of recycled concrete.