Objectives: High quality of lymph node yield could increase survival but strategies to improve it was seldom reported. This study was aim to assess the impact of a lymph node promotion activity (LNPA) in oral cancer surgery through a difference-indifferences research design. Design: A retrospective based study. Setting: Medical center in Taiwan. Subjects and methods: A total of 400 oral cancer patients underwent primary tumor resection and neck dissection including elective neck dissection (END) and radical neck dissection (RND) were recruited after propensity score matching by clinical T and N category between 2009 Janu-ary and 2018 October. Oral cancer patients were treated by two independent departments in our institute. Since 2015 Oct, a LNPA was initiated in one department (target group), and another department was as a control group. The impact of LNPA on LN yield and regional recurrence were analyzed and compared between these two groups by difference-indifferences (DID) linear regression analysis. Results: The mean age was 55.2+11.1 years, and 92% were male. 180 (45%) oral cancer patients had T3-4 disease, and 128 (32%) patients had N2-3 disease. In DID analysis, a lower LN yield among the target group before 2015 Oct (coefficient=-11.05, p<0.001). LNPA launched after 2015 Oct in target group showed a positive promotion of LN yield (coefficient=13.24, p<0.001). Moreover, a borderline protective effect of LNPA on regional recurrence among those with cN0 disease (coefficient=-9.4%, p=0.087) was noted. Conclusion: Strategy, like LNPA was associated increased LN yield and decreased regional recurrence in oral cancer. This kind of activity to promote surgeons to improve their quality of neck dissection was feasible and could be applied widespread.