The effects of single bending and compound bending of nano CaCO₃ （NC） and fly ash （FA） on the slump， mechanical properties， chloride penetration resistance， hydration reaction and microstructure of recycled aggregate concrete （RAC） were studied. The results show that NC can improve the mechanical properties， chloride penetration resistance and hydration reaction rate of RAC， but reduce its slump. FA can improve the resistance to chloride penetration and the late mechanical properties of RAC， but reduce its hydration reaction rate and early mechanical properties. The negative effects of single addition of NC and FA are improved after the two compounds are mixed. RAC has better slump， mechanical properties， chloride penetration resistance and hydration reaction. The compound bending of NC and FA can reduce the content of calcium hydroxide （CH） crystals in RAC， fill the pores of RAC slurry structure， repair the interface transition zone （ITZ） between new and old mortar， and improve the compactness of RAC.