Abstract: Hepatocellular carcinoma complicated with portal vein tumor thrombus (PVTT) is a common clinical predicament, and its understanding remains insufficient. Here, some new ideas on the formation mechanism of PVTT, visibility classification of PVTT, and causes and mechanism of intrahepatic dissemination and metastasis are presented. Based on these ideas, the authors put forward the concept of "portal vein priority", that is, the portal vein in the area where the tumor is located should be dissected, ligated or blocked before mobilizing the liver and removing the tumor, the concept of "portal vein exploration", that is, during parenchymal dissection, the ducts on liver section should be explored for tumor thrombus before ligation, and "thrombectomy under direct vision with portal vein in situ incision", that is, for Chen's type Ⅱ and some type Ⅲ tumor thrombi, the main portal vein and the contralateral branch should be dissected and blocked first, then the portal vein is incised at the location of tumor thrombus and the tumor thrombus is extracted under direct vision.