Directly using natural materials as supporting material and reducing agent to obtain supported catalysts is significance along with the research of green and sustainable technologies. Herein, diatomite supported Pt (Pt/diatomite) catalysts were synthesized by the bioreduction method, through using Cinnamomum camphora (CC) leaf extract as reducing agent. As a result, the as-prepared 0.3% Pt/diatomite not only presented good benzene catalytic oxidation performance but also was catalytically stable and durable through long time on-stream, water vapor and carbon dioxide effect experiments. Through XPS, H-2-TPR, H-2-TPD, TEM, and in situ DRIFTS of CO adsorption analysis, it can be noticed that the high catalytic oxidation activity of 0.3% Pt/diatomite is attributed with more surface absorbed oxygen, good Pt dispersion and strong interactions between Pt and diatomite. Moreover, in situ DRIFTS of benzene oxidation experiments revealed that the hydrocarbon fragments were the intermediates during the process.