The utility model provides an uninterrupted quantitative dosing system. The device comprises a chemical storage tank, a first chemical pipe, a first control butterfly valve, a seventh chemical pipe, asixth control butterfly valve, a plurality of control pipelines, an eighth chemical pipe and a fourth control butterfly valve, a liquid outlet of the medicine storage tank is connected with a liquidinlet of a first medicine pipe; a liquid outlet of the first medicament pipe is connected with liquid inlets of a plurality of control pipelines; a first control butterfly valve capable of controllingthe opening and closing of the first medicament pipe is arranged on the first medicament pipe; a seventh agent pipe is connected between the control pipelines in parallel, the seventh agent pipe canbe connected with the control pipelines through eighth agent pipes, sixth control butterfly valves are arranged at the two ends of the seventh agent pipe, and fourth control butterfly valves capable of controlling the eighth agent pipe to be opened and closed are arranged on the eighth agent pipes. According to the utility model, enough time can be provided for operators to troubleshoot and replace faulty equipment or pipe fittings by switching the control pipeline, so that the normal dosing is ensured, and the stability and normality of dosing indexes are ensured.