The invention relates to an MODS disinfection system. The MODS disinfection system is applied to disinfection in water treatment, and comprises a disinfectant preparing module, a UV disinfection module and a central control system. The MODS disinfection system adds a disinfectant prepared by the arranged disinfectant preparing module into sewage first, then mixed liquid of the sewage and the disinfectant passes through the UV disinfection module, the sodium hypochlorite disinfectant is irradiated by ultraviolet light to produce active oxygen with very strong oxidability, the active oxygen hasvery strong oxidability and can quickly kill microorganisms in water, and ultraviolet rays can quickly sterilize bacteria in the process of passing through the UV disinfection module; due to a very short irradiation time, a part of the sodium hypochlorite disinfectant still exists in the form of free chlorine in the water, so that a continuous sterilizing effect is guaranteed; arrangement of an independent contact disinfection tank is not required, the continuous sterilizing effect can be guaranteed, and the problem that the water quality exceeds standards due to secondary pollution or microorganism resurgence is avoided; the MODS disinfection system has the operating cost lower than that of the conventional sterilizing technology, and occupies a small floor area.