The invention discloses a filling body preparation method capable of reducing cementing agent consumption. Low-temperature water is conveyed into a clean water basin through a pipeline, then the low-temperature water in the clean water basin is conveyed to a heating source to be heated to 60 DEG C to 80 DEG C, and gradient geothermal energy brought about along with mine depth exploitation can be utilized. Aggregate, ingredients, a cementing agent and high-temperature water of filling materials are weighed simultaneously and fully stirred for 60 seconds or more, and good paste slurry liquid is prepared and conveyed to a pit through a filling pump. A temperature rising mode is adopted and systematically acts on a filling body, so that the initial temperature of the filling body is increased on the premise of reduction of the cementing agent consumption, the filling body with the same mechanical strength is obtained, and thus the filling cost of mine enterprises is lowered.