Three-dimensionally ordered macroporous (3DOM) MnxCe1-xO delta oxides with different ratios of Mn to Ce were successfully synthesized by colloidal crystal template (CCT) method, and 3DOM Pt/Mn0.5Ce0.5O delta with varied Pt loadings were prepared by in situ ethylene glycol (EG) reduction method. 3DOM MnxCe1-xO delta supports exhibited well-defined 3DOM nanostructure, and Pt nanoparticles (NPs) with 1-2 nm size were evenly dispersed on the inner walls of uniform macropores. Among 3DOM MnxCe1-xO delta catalysts, 3DOM Mn0.5Ce0.5O delta showed excellent catalytic activity for soot combustion; i.e., T-50 is 358 degrees C and S-CO2(m) is 94.2%. 3DOM Pt/Mn0.5Ce0.5O delta catalysts exhibited higher activity than 3DOM MnxCe1-xO delta and 3 wt % Pt/Mn0.5Ce0.5O delta showed the highest catalytic activity for soot combustion (T-50 is 342 degrees C and S-CO2(m) is 96.7%). Macropores effect, synergistic effects between Mn and Ce, and synergistic effects between Pt and Mn0.5Ce0.5O delta support are contributed to high catalytic activities of as-prepared catalysts.