Abstract: Objective This study is to investigate the relationship of tumor-infiltrating lymphocytes and pathological complete response (pCR) to neoadjuvant treatment(NAT) in breast cancer, and to observe the dynamic change of TILs between pre- and post-NAT. Methods A total of 100 cases of breast cancer with 696 paraffin blocks were collected between January 2014 and December 2018 in Affiliated Cancer Hospital & Institute of Guangzhou Medical University. TILs was evaluated by pathologists on H&E sections. SPSS 22.0 was used to detect the predictive value of TILs to pCR and the dynamic change of TILs between pre- and post-NAT. Results Bivariate regression analysis indicated that Total TILs (OR 1.182,95%CI 1.030~1.358, P=0.018) and Intratumoral TILs (OR 1.727, 95%CI 1.137~2.622,P=0.010) were statistically significant and independent predictors of pCR. Otherwise, the Total TILs(P<0.000 1), Stromal TILs(P<0.000 1)and Intratumoral region TILs(P=0.057)in pre-NAT tissue were significantly higher than those in post-NAT. Conclusion s Total TILs and Stromal TILs could be predictive factors for pCR to NAT in breast cancer. Meanwhile, NAT could promote Stromal TILs in breast cancer.