The invention discloses a method and system for producing low-alkalinity novel-mineral-system sulphoaluminate cement by utilizing steel slag. The method comprises the following steps: uniformly mixingpulverized steel slag and dried desulfurized gypsum, aluminum ash and calcium carbide slag according to a set ratio, and performing homogenization, wherein the homogenized cement raw material has analkalinity coefficient of 0.81-0.9, and a Fe2O3 content of 8-13%; and conveying the homogenized raw material to a rotary kiln, and performing calcination to obtain the cement clinker, wherein the calcination temperature is 1200-1270 DEG C, and the calcination time is 20-60 min. The method provided by the invention breaks through requirements for the content of calcium, aluminum and iron in production of traditional sulphoaluminate cement, and realizes a large amount of applications of the solid waste steel slag.