The invention discloses a method for preparing microbial mineralized stainless-steel-slag bricks. The method comprises the following steps: (1) uniformly mixing and stirring stainless-steel slag and lime, so as to obtain a composite cementing material; (2) pouring the composite cementing material into a stirring pot, then, adding an aqueous solution of microbe powder and sand into the stirring pot, carrying out uniform stirring to obtain slurry, then, pouring the slurry into molds, and carrying out press forming under the condition of 10MPa to 30MPa, so as to obtain test pieces; (3) demolding the test pieces so as to obtain test samples, and then, curing the test samples, thereby obtaining the stainless-steel-slag bricks. The method has the advantages of simple process, high strength grade, low energy consumption, environment-friendliness and the like, technical support is provided for use of the stainless-steel slag in the field of building materials, the problem that the utilization ratio of the stainless-steel slag is insufficient is effectively solved, the compressive strength, a water absorption rate, a softening coefficient and stability of the prepared stainless-steel-slag bricks all meet the requirements of currently-common building bricks.