Hepatitis D virus (HDV) is a defective RNA virus that significantly accelerates the progression of liver disease when co-infected with hepatitis B virus. Despite its low prevalence in China, the large population of hepatitis B virus-infected individuals still results in a substantial disease burden, with notable regional and population distribution disparities. In terms of HDV infection diagnosis, current standards remain relatively outdated, screening rates are low, and the sensitivity and standardization of detection methods urgently need improvement. This article systematically reviews the epidemiology, screening, diagnosis, and treatment advances of HDV, aiming to provide references for clinical practice.