Abstract: Objective To systematically analyze the medication pattern of Professor Lin Shangzhu, a renowned traditional Chinese medicine practitioner, in treating chronic atrophic gastritis (CAG) with Qi deficiency and collateral stasis pattern, using a combination of retrospective research and data mining techniques, and to optimize prescriptions based on the findings. Methods A total of 800 prescriptions for CAG patients with Qi deficiency and collateral stasis pattern treated by Professor Lin Shangzhu from November 21, 2022, to November 20, 2024, were collected through the outpatient medical record system. A traditional Chinese medicine database was established using Excel, and data entry and verification were performed. The data was imported into the Traditional Chinese Medicine Inheritance Calculation Platform V3.0 to analyze the medication patterns. Results The prescriptions primarily targeted the Spleen Meridian (42.37%), Stomach Meridian (31.82%), and Liver Meridian (25.91%). Herbs targeting the Spleen Meridian were mainly tonics and Qi-regulating agents, while those for the Stomach Meridian were primarily blood-activating and stasis-resolving herbs and heat-clearing herbs. Property distribution was as follows: warm (43.21%), neutral (28.50%), slightly cold (18.92%), with cold properties accounting for only 9.37%. Flavor distribution included sweet flavor (36.72%, such as Glycyrrhizae Radix Et Rhizoma and Atractylodis Macrocephalae Rhizoma), pungent flavor (29.53%, such as Angelicae Sinensis Radix and Euodiae Fructus), and bitter flavor (23.81%, such as Scutellariae Radix and Coptidis Rhizoma), which was consistent with the compatibility principle of "using sweet and warm to strengthen the spleen, and pungent to unblock collateral stasis." The 800 prescriptions involving 187 traditional Chinese medicines, with a cumulative usage frequency of 16 798 times; Among them, there are 20 herbs were used over 250 times, with the top five being: stir fried bran Atractylodis Macrocephalae Rhizoma(712 times), Astragali Radix(687 times), Angelicae Sinensis Radix(654 times), Bupleurum Chinense (623 times), and Glycyrrhizae Radix Et Rhizoma (598 times). The proportion of tonifying deficiency drugs is the highest at 25.00%, and the total proportion of promoting blood circulation, removing blood stasis, and regulating Qi drugs is 40.00%. The Apriori algorithm identified 10 effective herb-pair combinations, including "stir fried bran Atractylodis Macrocephalae Rhizoma-Astragali Radix", "Angelicae Sinensis Radix-Salviae Miltiorrhizae Radix Et Rhizoma", "Codonopsis Radix-stir fried bran Atractylodis Macrocephalae Rhizoma", and "Citri Reticulatae Pericarpium-Astragali Radix". Cluster analysis yielded 5 new prescription combinations. Conclusion Professor Lin Shangzhu's treatment of CAG with Qi deficiency and collateral stasis pattern is centered on "strengthening the spleen and replenishing, activating blood and unblocking collaterals". Through dynamic prescription adjustment and herb-pair compatibility, it integrates traditional Qi and blood theory with modern pharmacological mechanisms, scientifically interpreting the academic thought of "spleen deficiency leading to stasis, simultaneous treatment of Qi and collaterals", thereby providing a basis for optimizing precise treatment in clinical practice.