The invention relates to a concentrated sulfuric acid solution automatic preparation device, which comprises a magnetic stirring device, a thermocouple sensor, an electromagnetic valve, a volumetric bottle, a reagent bottle, a magnet, an iron stand, a support arm and a fixing screw, wherein the iron stand is positioned at the right side of the magnetic stirrer; the support arm is positioned on the iron stand, and is connected with the thermocouple sensor and the volumetric bottle; the electromagnetic valve is positioned in the volumetric bottle. The concentrated sulfuric acid solution automatic preparation device has the advantages that the structure is simple; the operation is convenient; the service life is long; the goal of automatically preparing concentrated sulfuric acid solutions with different volume ratios is achieved; in addition, the danger during the concentrated sulfuric acid preparation is reduced.