This is a prospective, randomized, double-blind, placebo-controlled multicenter clinical study targeting cirrhosis patients with Spontaneous Bacterial Peritonitis(SBP), aiming to evaluate whether adding Bifidobacterium quadruple probiotics can improve infection control rates and reduce SBP recurrence. Meanwhile, by extending the follow-up period into a real-world clinical observation phase, the study will assess whether Bifidobacterium quadruple probiotics can lower SBP recurrence and extend the lifespan of cirrhosis patients. The primary endpoint of the study is the recurrence rate of SBP during the double-blind treatment period. The study plans to enroll 360 patients.