To summarize the identification and nursing experience of isolated persistent left superior vena cava（PLSVC） during PICC insertion in the right upper limb. The patient had no known vascular anatomical abnormalities before catheterization and no typical P-wave changes during intracardiac electrogram localization for PICC insertion. Isolated PLSVC was successfully diagnosed by identifying initial PICC malposition，adjusting ECG monitoring，assisting the patient with limb and body position coordination，and recognizing special ECG manifestations. After catheterization，a multidisciplinary discussion was held on the feasibility and safety of retaining the PICC. Finally，the patient retained the catheter，successfully completed intravenous infusion therapy，and was discharged.