Microvascular invasion (MVI) is considered an important pathological prognostic parameter for hepatocellular carcinoma (HCC). Growing evidence has revealed that MVI can be regarded as a stratified index for clinical intervention. However, few studies have focused on how to conduct a standardized assessment of MVI, which renders conclusions of related clinical studies unreliable. This review introduces the definition of MVI, a seven-point baseline sampling protocol for HCC, and MVI risk classification protocol, all of which have been promoted in China. These concepts should be applied in the diagnosis of HCC in the future. Furthermore, recent studies on the molecular mechanism of MVI have been summarized to provide a reference for future research on underlying molecular pathology.