This study explored how MoSi2-TaSi2 ratios in silicide alloys influence the oxygen resistance of ZrB2-MoSi2-TaSi2 coatings, using self-propagating high-temperature synthesis and spark plasma sintering. The oxidative self-separation effect of TaSi2 and MoSi2 enhances nanoscale Zr and Ta oxide particle dispersion, forming a Zr-B-Ta-Si-O glass with optimal oxygen-blocking in the 50ZrB2-(MoSi2-10TaSi2) coating (ZMT10). Compared to ZrB2-MoSi2, ZMT10 showed 28.87 % and 48.21 % reductions in weight gain and oxygen penetration, increasing protection to 99.71 %. Excessive TaSi2 leads to Ta5+ dissolution, oxide aggregation, and a dendritic structure, facilitating oxygen diffusion and oxidation, raising the oxygen penetration in 50ZrB2-(MoSi2-30TaSi2) to 0.73 %, lowering protection to 99.18 %. •MoSi2-TaSi2 double silicide powders by SHS method to enhance the oxygen barrier of ZrB2 coatings.•Co-strengthening effect of MoSi2-TaSi2 double silicides reduced the oxidation activity of the coatings.•The low-content TaSi2 resulted in a 48.21 % reduction in oxygen permeability.•Diffusion of Zr/Ta oxides in glass films formed stable Zr-B-Ta-Si-O complex glass film.•Excessive addition of TaSi2 exacerbated oxide aggregation and formed a loose dendritic structure.