Objective To explore the application value of three ⁃dimensional computed tomography ⁃lym⁃ phography（3D CT ⁃ LG）in the identification and classification of lymphatic drainage pathway of breast cancer. Methods 3D CT ⁃LG was performed in 100 cases diagnosed as breast cancer to reconstruct and distinguish the type of breast lymphatic drainage pathway before operation. Intraoperative methylene blue combined with indocya⁃ nine green was used to verify the accuracy of 3D CT⁃LG. Results A total of 93 cases（93%）could be classified by 3D CT⁃LG：63 cases（65.6%）as type Ⅰ（single lymphatic connected with one sentinel lymph node）；12 cases （13.5%）as type Ⅱ（single lymphatic connected with multiple sentinel lymph nodes）；4 cases（5.2%）as type Ⅲ （multi⁃root lymphatic connected with a sentinel lymph node）and14 cases（15.6%）as type Ⅳ（multi⁃root lymphatic connected with multiple sentinel lymph nodes）. Ninety⁃five cases could be classified by tracer method（95%）：62 cases（65.3%）as typeⅠ；12 cases（12.6%）as type Ⅱ；6 cases（6.3%）as type Ⅲ and 15 cases（15.8%）as type Ⅳ. Kappa value in consistency analysis was 0.912（P < 0.05）. Conclusion 3D CT⁃LG can accurately identify lymphatic drainage pathway of breast cancer and plays an important role in the classification.