Bonding interface changes on different types of dentin after Er:YAG laser irradiation is evaluated. Normal dentin (ND) group and caries affected dentin (CAD) group samples are respectively irradiated with Er:YAG laser, and then etching with 38% phosphoric acid(phosphoric acid group), low-dose Er:YAG laser radiation (laser group) and no treatment (control group). The bonding interface changes are assessed via confocal laser scanning microscope (CLSM). There is no significant difference in thickness (p>0.05) within the same group with different etching methods or among different groups with the same etching, however, significant differences are existed in the length of resin tags (p<0.05). Maximum resin-tags are achieved in the phosphoric acid group, while control group minimum. Resin-tags in the bonding interface of ND are longer than that of CAD. The adhesive can infiltrate well into dentin bonding interface to achieve a quite ideal resin tags in the ND groups etching with 38% phosphoric acid.