Abstract：Objective：To analyze the medication rules of ZHANG Bei in treating nasopharyngeal carcinoma（ NPC） during radiotherapy and chemotherapy based on the Traditional Chinese Medicine Inheritance Support System（ TCMISS）， and to summarize her clinical medication experience. Methods：Prescriptions for NPC patients at the radiotherapy and chemotherapy stage from ZHANG Bei′s outpatient clinic between March 31， 2020 and October 31， 2024 were collected and entered into the TCMISS. Statistical analyses were performed on medication frequency，nature-flavor and channel entry，and efficacy categories，along with association rule analysis and cluster analysis. Results：A total of 171 prescriptions were included. The top 5 most frequently used Chinese medicinals were Glycyrrhizae Radix et Rhizoma，Pseudostellariae Radix，Galli Gigerii Endothelium Corneum，Ophiopogonis Radix，and Dendrobii Herba. The medicinal natures were predominantly cold and neutral；the flavors were mainly sweet and bitter；and the primary channel entries were spleen， lung， and stomach. The efficacy categories were mainly deficiency-supplementing medicinals，heat-clearing medicinals，and digestive medicinals. High-frequency herb pairs included Pseudostellariae Radix-Glycyrrhizae Radix et Rhizoma， Galli Gigerii Endothelium Corneum-Glycyrrhizae Radix et Rhizoma， and Pseudostellariae Radix-Galli Gigerii Endothelium Corneum. Association rules with higher confidence included Rehmanniae Radix→ Ophiopogonis Radix，Ophiopogonis Radix → Glycyrrhizae Radix et Rhizoma，and Ophiopogonis Radix → Pseudostellariae Radix. Potential herb combinations mined out were Belamcandae Rhizoma，Albiziae Cortex， Citri Sarcodactylis Fructus，Lycii Fructus，and Arctii Fructus. Conclusion：The medication of ZHANG Bei in treating NPC during radiotherapy and chemotherapy primarily focuses on boosting qi and nourishing yin， strengthening the spleen and harmonizing the stomach， supplemented by clearing heat， resolving toxin， and soothing the throat， reflecting the diagnostic and therapeutic thinking of "fortifying the healthy qi and eliminating pathogens，and addressing both root and branch."