The invention provides an automatic quantitative delivery control device for a train and an automatic quantitative delivery control method. The device comprises a mechanical system and a control system, wherein the mechanical system comprises a first belt conveyor, a first transitional belt conveyor, a bulk material scale, a second transitional belt conveyor, a second belt conveyor and a discharging trolley which are installed sequentially along a dry bulk salt transportation path; the control system comprises a PLC (programmable logic controller) system and a DCS ( distributed control system), the PLC system is connected with the mechanical system and is used for collecting and processing operation state data of the mechanical system and generating an operation state data stream, and the DCS is used for inputting the operation state data stream into the DCS through a field bus for processing and achieves remote data exchange and monitoring. The invention further comprises the automatic quantitative delivery control method. The control precision is high, the problem that salt is accumulated on a feed belt is solved, the loading efficiency is high, and two railway wagons holding more than 150 tons of salt can be fully loaded in an hour.