The invention relates to a sodium thiosulfate and acid reaction-based preparation device for a sulfur positive electrode composite material and a control method of the preparation device. The preparation device for mixing of sodium thiosulfate and a porous conductive carrier, reaction of the sodium thiosulfate and an acid and separation of a sulfur positive electrode material and a waste liquid is designed, the mixing time of the porous conductive carrier and a sodium thiosulfate solution is controlled within 0.5-10 hours, the mole ratio of the acid and the sodium thiosulfate solution is 2-3, the injection pressure is 2-40MPa, the mass ratio of the porous conductive carrier and sulfur is 0.01-1, the type of the porous conductive carrier is controlled, thus, small particle size and uniformly sulfur/porous conductive carrier distribution of the sulfur positive electrode composite electrode material are achieved, and the prepared sulfur positive electrode composite electrode material has good electrochemical performance. The preparation device has good application prospect in the field of a lithium ion battery.