The invention discloses a low-calcium silicate cement produced by using aluminum waste slag and a preparation method thereof. The low-calcium silicate cement comprises the following components in percentage by weight: 65 to 85 percent of limestone, 6 to 10 percent of the aluminum waste slag, and 9 to 25 percent of steel slag or iron slag. The method for preparing the low-calcium silicate cement comprises the following steps: (1) drying and treating the aluminum waste slag so as to dehydrate the aluminum waste slag; (2) adding the dehydrated aluminum waste slag, the limestone and the steel slag into a crusher according to the proportion, and crushing the materials; (3) adding the crushed materials into a cement rotary kiln, and heating and calcining the materials; and (4) adding a ball milling assistant into the sintered clinker, and ball-milling and packaging the mixture to obtain the low-calcium silicate cement. Compared with the prior cement, the low-calcium silicate cement produced by using the industrial wastes as the aluminum waste slag has higher mechanical strength, simultaneously has the characteristics of simple process, low sintering temperature and energy consumption of a unit product, and high rate of finished products, and is suitable for industrial popularization because the prior equipment is directly used.