Objective To evaluate the waterlase chemo-mechanical technique for the treatment of tooth caries in elderly patients. Methods According to the randomly sampling principle, a retrospective clinical data of our records of elderly patients with caries, were divided into two groups: 50 patients in treatment group A, treated with the waterlase chemo-mechanical method; and 48 patients in the control group B, treated with the conventional method.The therapeutic effect was evaluated after 6. Results Among the 50 cases in A group, two fillings fell off and one secondary caries occurred, with the curative rate of 90.0%. Among the 48 cases in B group, eight fillings fell off and four secondary caries occurred, with the curative rate of 75.0%. The difference between those of the treatment group and those of the control group was statistically significant (P＜0.05). Conclusions The waterlase chemo-mechanical technique for elderly patients is effective. The perspective in application is significant and worthy of clinical promotion.