In order to study the effect of different fly ash replacement ratio on the fracture performance of brick-rich recycled concrete,four sets of brick-recycled concrete three-point bending beam specimens with dimensions of 100mm×100mm×515mm were produced. Recycled concrete was based on RC25, and the replacement ratio of fly ash was 0%,10%,20% and 30%.. Through the fracture toughness test of three-point bending beam,the variation law of the replacement rate of brick-rich recycled concrete with fly ash was studied. The results show that when the replacement ratio of fly ash is 10%,the increase of cracking toughness and instability toughness of brick-rich recycled concrete is 4.61% and 7.44%, respectively. When the replacement rate of fly ash exceeds 10%, with the increase of the replacement rate of fly ash,the fracture toughness decreases gradually,and the reduction maximum is 12.21%. The relationship between double K fracture toughness and fly ash replacement ratio of brick-rich recycled concrete is given.