It is still not clear whether rifaximin can prevent the progression of liver cirrhosis, reduce the overall complications and improve the survival in patients with decompensated cirrhosis. This is a multi-center open-labelled randomized prospective study to evaluate the efficacy and safety of rifaximin in preventing the progression and complications in cirrhotic patients, and explore its reasonable dosage and possible mechanism. A total of 150 patients with decompensated liver cirrhosis will be enrolled in the study and randomly divided into three groups (the control group (A), the low-dose rifaximin treatment group (B), and conventional dose rifaximin treatment group (C)) with a ratio of 1:2:2. The patients in group B are given rifaximin with the dose of 600mg/d (600mg, qd) for 24 weeks, and the patients in group C are delivered 1200mg/d (600mg, bid) of rifaximin .During the entire study period, all other therapeutic strategies are kept unchanged in all the groups as long as possible. The proportion of patients with progression of cirrhosis, the incidence of total complications and each complication, survival rate and time, liver function and adverse events will be compared among the three groups. This study might provide a new feasible method with clinical application prospects for preventing the progression and reducing the incidence of liver cirrhosis related complications, improve the prognosis of patients with decompensated liver cirrhosis, and save medical resources.