Objective To investigate the risk factors for peripherally inserted central catheter (PICC) related venous thrombosis (CRT) in elderly patients with gastrointestinal tumors, and analyze intervention measures. Methods A retrospective analysis was conducted on 2 033 elderly patients with gastrointestinal tumors treated in our hospital from January 2015 to January 2023. All patients underwent PICC catheterization, and those with CRT were included in the thrombus group (n=270), while those without in the control group (n=1 763). SPSS statistics 20.0 was used for data processing. Student′s t test or Chi-square test was employed for intergroup comparison depending on data type. Logistic regression analysis was applied to identify the risk factors for CRT in the patients. Results Among the 2 033 patients, 13.28% (270/2 033) had CRT. Logistic regression analysis showed that history of deep vein thrombosis (OR=4.778,95%CI 1.339-17.048), D dimer ≥5 mg/L (OR=3.951,95%CI 1.401-11.143), total cholesterol ≥6.7 mmol/L (OR=3.983,95%CI 1.582-10.026), body mass index (BMI) ≥25 kg/m² (OR=4.433,95%CI 1.336-14.710, catheter tip located in the subclavicular vein (OR=3.808,95%CI 1.316-11.016), concurrent chemoradiotherapy (OR=5.307,95%CI 1.299-21.678) and long-term bedridden rest (OR=4.749,95%CI 1.347-16.748) were independent risk factors for CRT in elderly patients with gastrointestinal tumors. Conclusion After PICC catheterization in elderly patients with gastrointestinal tumors, monitoring and early intervention are necessary for the patients with history of deep vein thrombosis, D-dimer ≥5 mg/L, total cholesterol ≥1.7 mmol/L, BMI ≥25 kg/m², catheter tip located in subclavian vein, concurrent chemoradiotherapy and long-term bedridden rest, in order to reduce the risk of CRT.