Objective: To explore the application of modified midline catheters and peripherally inserted central catheter (PICC) in patients with advanced tumor venous nutrition support. Methods: A total of 100 patients with advanced nutritional support for advanced tumor venous nutrition from January 2019 to December 2019 were randomly divided into observation group and control group. The observation group was treated with a modified medium-length catheter for intravenous infusion. The group used PICC for intravenous infusion. The incidence of catheter-related complications and the success rate of one-time catheterization were compared between the two groups of patients. At the same time, the catheter-related medical costs and patient satisfaction of catheterization were compared. Results: The incidence of catheter-related complications in the observation group was significantly lower than that in the control group (P<0.05). The tube placement and maintenance costs in the observation group were significantly reduced compared with the control group (P<0.05). The success rate of one-time catheterization and patient satisfaction of catheterization in the observation group were significantly higher than those in the control group. Conclusion: The improved medium-length catheter is better than PICC in patients with advanced tumor intravenous nutrition support. It has fewer complications, relatively few medical expenses, high success rate of tube placement and high patient satisfaction.