The utility model discloses a medicine adding system, and belongs to the field of a sewage disposal system. The medicine adding system comprises a water tank, an antisludging agent medicine adding system, a stink agent medicine adding system and a controller; the antisludging agent medicine adding system comprises an antisludging agent medical kit, a metering pump and a flow instrument; the stink agent medicine adding system comprises a stink agent medical kit, a make-up pump and a metering pump; the water outlet end of the water tank is connected with the make-up pump and the metering pump, the metering pump is communicated with the stink agent medical kit, the flow velocity of a detection pipeline of the metering pump is converted into a signal with 4-20 milliamperes, the signal is sent to the controller, and the controller controls the medicine pumping frequency of the metering pump according to a preset value. The medicine adding system is simple in structure and convenient to use, the integral controlling can be achieved, an antisludging agent is added into first net water of the water tank, water of the water tank is guaranteed to be thorough, an purifying stink purifying agent is added into second net water circulation, and stink of the water of the water tank is removed; the structure is reasonable, and the practicality is strong.