The biological characteristics of hepatocellular carcinoma (HCC) lead to a high incidence of portal vein tumor thrombus. It progresses rapidly, and the opportunity for radical surgical resection can be lost in a short term, resulting in poor prognosis. Reasonable down-staging treatment is a research focus for patients with unresectable HCC complicated with portal vein tumor thrombus to achieve a resectable range. This article reviews the potential population of HCC complicated with portal vein tumor thrombus with conversion therapy for HCC, analyzes the application of hepatic artery infusion chemotherapy, transcatheter arterial chemoembolization, radiotherapy, regional and systemic drug therapy in conversion therapy, and points out that the combination of multidisciplinary comprehensive treatments is the key to improve the prognosis of HCC patients with portal vein tumor thrombus.