Acute-on-chronic liver failure (ACLF) is divided into three types according to the underlying liver disease: non-cirrhosis (type A), compensated cirrhosis (type B) and decompensated cirrhosis (type C). However, whether the underlying chronic liver diseases impact the ACLF prognosis is not clear. The present study aimed to compare the characteristics and outcomes of type A and type B hepatitis B virus (HBV)-ACLF patients. According to the European Association for the Study of Liver-Chronic Liver Failure (EASL-CLIF) diagnostic criteria, 86 type A HBV-ACLF and 71 type B HBV-ACLF were prospectively enrolled. The demography and laboratory data, organ failures, ACLF grades and prognosis were evaluated. Univariate and multivariate Cox regression analyses were performed to analyze the prognostic factors. The 28-day and 90-day mortality rates of type A and type B ACLF were 20.9 vs. 60.6% and 34.9 vs. 73.2%, respectively (both P < 0.001). Patients with type A ACLF were younger, had higher viral load and higher levels of alanine aminotransferase and aspartate aminotransferase, platelet count, serum albumin and sodium, international normalized ratio and alpha-fetoprotein, lower rate of ascites, lower Child-Pugh scores and CLIF sequential organ failure assessment scores, higher rate of coagulation failure. Type B ACLF had more renal and cerebral failure. Cirrhosis was one of the independent prognostic factors [hazard ratio, 2.4 (95% CI, 1.451-3.818) P < 0.001]. ACLF developing on noncirrhotic chronic hepatitis B had more serious liver inflammation but fewer extrahepatic organ failures and better outcome than ACLF developing from compensated HBV cirrhosis.