PtRu nanoparticles decorated on carbon-based supports are of great interest for direct methanol fuel cells (DMFCs). In this study, PtRu alloy nanoparticles decorated on carbon Vulcan XC-72 (C), multi-walled carbon nanotubes (MWCNTs), and C-MWCNTs composite supports were synthesized by co-reduction method. As a result, PtRu nanoparticles obtained a small mean size (d_mean = 1.8–3.8 nm) with a size distribution of 1–7 nm. We found that PtRu/C₆₀MWCNTs₄₀ possesses not only high methanol oxidation activity, but also excellent carbonaceous species tolerance ability, suggesting that C-MWCNTs composite support is better than either C or MWCNTs support. Furthermore, detailed investigation on PtRu/C_100−xMWCNTs_x (x = 10–50 wt.%) shows that the current density (J_f), catalyst tolerance ratio (J_f/J_r), and electron transfer resistance (R_et) are strongly affected by C-MWCNTs composition. The highest J_f is obtained for PtRu/C₇₀MWCNTs₃₀, which is considered as an optimal electrocatalyst. Meanwhile, both PtRu/C₇₀MWCNTs₃₀ and PtRu/C₆₀MWCNTs₄₀ exhibit a low R_et of 5.31–6.37 Ω.cm². It is found that C-MWCNTs composite support is better than either C or MWCNTs support in terms of simultaneously achieving the enhanced methanol oxidation activity and good carbonaceous species tolerance.