Flower-like MoS2/Ag2S/Ag nanocomposites have been elaborately designed and synthesized successfully for the first time. The prepared MoS2/Ag2S/Ag nanocomposites as a novel photocatalysts present effective photocatalytic performance for the photodegradation of congo red (CR), tetracycline hydrochloride(TC-HCl) and disinfection for Pseudomonas aeruginosa (P. aeruginosa). For the photodegradation of TC-HCl, the effect of the pH of the initial solution and photocatalysts dosage was investigated. Furthermore, intermediates of TC-HCl degradation were verified by GC–MS analysis and the possible pathway of the photodegradation was also proposed. The electron paramagnetic resonance (EPR) technique and trapping experiments verified the electron transport path is Z-scheme system (PS-C-PS). Among them, Ag as an electron mediator enhanced the electron transmission rate and accelerated the separation efficiency of photogenerated carriers.