Objective To improve the subcutaneous tunnel needle and the method of establishing subcutaneous tunnel for PICC,and to explore its application effect. Methods The improved subcutaneous tunnel needle consists of 3 parts,including needle handle,solid needle core and needle head. The needle head has an arc chamfering structure,which can realize the stable connection between the catheter and the needle head. Patrticipants from a tertiary hospital in Guangdong Province were selected by convenience sampling. 97 tumor patients from November 2019 to January 2021 were allocated into an experimental group,while 115 tumor patients from August 2018 to October 2019 were in the control group. The experimental group received the improved subcutaneous tunnel needle via a 30°~45° degree with venipuncture for PICC catheterization under B-ultrasound,while the control group was treated with Seldinger technique for PICC catheterization under B-ultrasound. The amount of bleeding and the highest pain score,the incidence of bleeding and exudation at the puncture point 24 hours after the operation,the incidence of catheter prolapse within a month after the operation,the incidence of allergic dermatitis,the incidence of mechanical phlebitis,and the comfort of the patients’ arms at a month after the operation were compared between the 2 groups. Results The amount of bleeding and the highest pain score in the experimental group were higher than those in the control group,and the difference was statistically significant（P<0.001）. The incidence of bleeding and exudation at the puncture point 24 hours after the operation,the incidence of catheter prolapse within a month after operation and the incidence of allergic dermatitis in the experimental group were lower than those in the control group（P<0.05）,but the incidence of mechanical phlebitis within a month after operation in the 2 groups was not statistically significant（P=0.484）;a month after operation,the arm comfort of the experimental group was higher than that of the control group,and the difference was statistically significant（P<0.001）. Conclusion The improved subcutaneous tunnel needle and subcutaneous tunnel establishment method can reduce the incidence of blood and fluid leakage,catheter prolapse and allergic dermatitis at the puncture point,and improve the postoperative arm comfort of patients,but they could not increase the incidence of mechanical phlebitis.