Intrahepatic cholangiocarcinoma (iCCA) is a malignant tumor originating from bile duct epithelial cells, with an increasing global incidence and characterized by high invasiveness and rapid progression. Perineural invasion (PNI) is one of its important pathological features, closely associated with tumor recurrence, lymph node metastasis, and shortened survival. PNI is not only a key mechanism by which tumor cells spread along neural pathways, but also an active process of tumor microenvironment remodeling, involving complex interactions between tumor cells, nerve cells, Schwann cells, and other components of the microenvironment. This article reviews the diagnostic grading system, clinical significance, and mechanistic research progress of PNI in iCCA, aiming to provide new insights for the early diagnosis of iCCA with PNI and the development of future therapeutic strategies.