<p>Underground filling mining is crucial for resource recovery and surface protection. Long-term loading can cause creep deformation. This study added mineral additives during the preparation of the filling body and conducted uniaxial compression creep tests to reveal the creep deformation characteristics and microstructure evolution mechanism of the filling body during the loading process. The results indicate that, for the three mineral additives examined in this study within the tested dosage range (4 wt.%-8 wt.%), the 28-day UCS of the backfill increased relative to the control, accompanied by reduced creep deformation and creep rate. At the same stress level, the steady-state creep strain rate of the specimen with 8 wt.% sodium bentonite was reduced by approximately 65% compared to the control group, whereas the 4 wt.% dosage group showed only a 40% reduction. The modification effect of silica fume was relatively limited, and calcium bentonite was between the two. These three different mineral additives optimized the pore structure and improved the creep resistance through specific micro-mechanism pathways. The research results provide valuable insights into the long-term mechanical behavior of backfill body materials and offer a reference for the development of high-performance and sustainable underground backfill body systems.</p>