Objective To observe the effect of Siteng Fang on the count of circulating tumor cells (CTCs) in patients with gastric cancer, and to explore the modern cell biological mechanism of its detoxification effect. Methods From Sep. 2020 to Sep. 2021, 60 patients of stageⅠ-Ⅱ gastric cancer after radical surgery with clear pathological diagnosis in Department of Oncology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine were randomly divided into Siteng Fang group and control group according to the random number table method, with 30 cases in each group. The Siteng Fang group was treated by Siteng Fang+conventional treatment with traditional Chinese and Western medicine, and the control group was treated by conventional treatment with traditional Chinese and Western medicine. Peripheral blood was collected from both groups, and CTCs were isolated and enriched by immunomagnetic bead negative enrichment technique, combined with fluorescence in situ hybridization to detect and count CTCs, and CTCs ≥ 1/3.2 mL was defined as positive. Results The positive rate of CTC detection was 81.67% (49/60), including 90.00% (27/30) in the control group and 73.33% (22/30) in the Siteng Fang group. Siteng Fang reduced the CTC counts in patients after radical surgery of early gastric cancer (P<0.01). Conclusion Siteng Fang can reduce the number of CTCs in patients after radical surgery of gastric cancer, suggesting that Siteng Fang may have anti-metastasis effect on gastric cancer by inhibiting CTCs.