Attributed to extrusion technology,there are many interfaces in 3D printed concrete,such as interlayer and interstrip interfaces,which affect the durability of printed concrete. In order to investigate the effect of printed interfaces and water binder ratio on the carbonation resistance of 3D printed concrete,the carbonation behavior of 3D printed concrete with three water binder ratios along X,Y,and Z directions was studied through carbonation tests. Based on mercury intrusion testing and X-CT scanning,the pore characteristics and distribution patterns in 3D printed concrete were obtained,and the change mechanism of carbonation resistance of 3D printed concrete was explained from a microscopic level. The research results indicate that pores are closely related to the carbonation behavior of 3D printed concrete. The interstrip and interlayer interfaces generate more pores due to the stacking of stripes,resulting in faster diffusion of CO2 and greater carbonation depth at these two positions. Therefore,the carbonation resistance of printed concrete exhibits significant anisotropy due to the influences of interfaces. The carbonization resistance of matrix material is better than that of interlayer position and the carbonization resistance of interlayer position is better than that of interstrip position. The lower the water binder ratio is,the better the carbonization resistance of material is. When CO2 diffuses in concrete,the uncarbonized islands are formed in printed concrete due to the effect of large pores between layers.