Objective: To investigate the treatment effect of breast duct expansion and irrigation using breast duct dilator combined with manual mammary dredge in acute lactation mastitis. Methods: From July 2017 to June 2018, 106 patients with acute lactation mastitis in Beijing Luhe Hospital affiliated to Capital Medical University were analyzed. In the treatment group, 57 patients were treated with mammary duct dilatation and flushing combined with manual breast dredge; 49 patients in the control group were treated with traditional artificial milk and antibiotics. Results: The usage of antibiotic in the treatment group was significantly lower than that in the control group (P<0.01). The reduction degree in the hypoechoic area of the ultrasound was significantly higher in the treatment group than in the control group (P<0.05). There was no significant difference in leukocyte recovery between the treatment group and the control group (P>0.05). The pain VAS score of the treatment group was 3.56±1.28. In the treatment group, the skin temperature before the first therapy was (35.66±0.84) ℃ and after that was (34.11±1.01) ℃, with an decrease about (1.55±0.80) ℃. Conclusion: Breast duct dilator combined with flushing and breast dredge can effectively reduce inflammation, relieve pain, decrease systemic antibiotic application and breastfeeding suspension, and family’s mental and economic burden, which is simple and worth promoting.