The invention relates to a series-connected bottom sealing type flexible medium abrasive blasting device. The device comprises a storage system, a spiral feeder system and a matched compressed air system. According to an upper storage tank and a lower storage tank which are arranged in a series-connected type, intermittent charging and continuous abrasive blasting are realized, so that the labor production rate and the equipment utilization rate are effectively improved; meanwhile, based on a stirrer inside the lower storage tank, the phenomenon of bridging can be effectively avoided.