Abstract: Hydrogen-rich syngas production via diesel steam reforming （DSR） is of great interest because of the high H₂/CO ratio and the availability of external heat sources. However, due to the elongated carbon chains and intricate composition in diesel fuels, there are some technical challenges such as low hydrogen yield, hot sintering at high temperature and carbon deposition in the process of hydrogen production. In order to achieve efficient reforming of diesel for hydrogen production, an innovative catalyst using pyrochlore carriers with different A-site cations （La³⁺/Pr³⁺/Sm³⁺） and a B-site consisting of the Ce element as a carrier supported by precious metals Rh was synthesized. Because the carrier has a better oxygen mobility, the performance of diesel reforming is improved, and the occurrence of catalyst carbon deposition is alleviated. Raman and EPR results shows, comparing Pr₂Ce₂O₇、Sm₂Ce₂O₇ and CeO₂ carriers, La₂Ce₂O₇ carrier contains the highest amount of oxygen vacancies and superoxide ions （\mathrmO_2^- ）. Furthermore, XPS and O₂-TPD results indicate, contrast with other Rh-supported catalysts, 3% Rh/La₂Ce₂O₇ catalyst formed more abundant and active surface adsorbed oxygen species, which is closely related to the best performance of 3% Rh/La₂Ce₂O₇ catalyst in n-hexadecane steam reforming. The 3% Rh/La₂Ce₂O₇ catalyst exhibited the highest conversion rate and reached up to 97.2%, the highest hydrogen volume content at 70.2% and the lowest by-product volume content. Specifically, the CH₄ volume content was 0.03%, C₂H₄ content was not been founded due to below the detection line 0.000 01%, and the volume content of C₂−C₅ hydrocarbons was merely 0.000 5%. Notably, the 1% Rh/La₂Ce₂O₇ catalyst with further reduction of Rh content, when applied in the steam reforming of actual fuel diesel, the performance is only slightly worse than that of n-hexadecane reforming, the conversion rate still reached up to 97.2%, hydrogen volume content achieves 67.9%, with remarkably low by-product volume contents of 0.15% methane, 0.04% ethylene, and 0.07% C₂−C₅ hydrocarbons. This catalyst exhibits outstanding reforming performance and demonstrates excellent resistance to carbon deposition, thereby showing a great potential in large-scale engineering application.