【Objective】To evaluate the two-dimensional shear wave elastography（2D SWE）in predicting the prognosis of the patients with acute-on-chronic hepatitis B liver failure（ACLF-HBV）.【Methods】312 patients diagnosed with ACLF-HBV at the De? partment of Infectious Diseases in the Third Affiliated Hospital of Sun Yat-sen University from October 1st 2013 to December 31th 2015 were recruited. The baseline data of all patients，including 2D SWE，laboratory data，ultrasonographic data，Model for End- stage Liver Disease score（MELD），Child-Turcotte-Pugh score（CTP），and King′s College Hospital score（KCH），were collected when enrolled. All patients were followed up for at least 90 days and their clinical outcomes（recovering or worsening）were recorded. 2D SWE values of all patients were dynamically collected every 2 ~ 4 weeks during the follow-up until death，liver transplantation， or discharging from hospital.【Results】The worsening patients showed higher 2D SWE values than the recovering ones［（44.0 ± 7.5） kPa vs（36.8 ± 10.3）kPa，t = -6.5，P = 0.000］，2D SWE value less than 39.2 kPa could be a prediction of the patient′s recovery in90 days.The predictive value of 2D SWE（AUROC = 0.73）was higher than that of KCH（AUROC：0.65，z = 2.1，P = 0.033）. Among all the dynamically measured patients，2D SWE rose from（42.1 ± 8.0）kPa to（47.5 ± 9.3）kPa in the worsening group during the 90- day follow-up，while nearly stable in the recovery group.【Conclusion】Noninvasive liver stiffness measurement by 2D SWE is a use? ful method in evaluating the prognosis of ACLF-HBV patients. Taking a cutoff of 39.2 kPa，patients with higher 2D SWE values could have worse clinical outcomes，otherwise better. It seems that dynamically measuring 2D SWE values could also be helpful，but more research in the future should be needed.