The fuel of hydrogen has remarkable characteristics including renewable, zero emission and high power density, thus making it hotly pursued for the new round of world energy technology revolution. Hydrogen fuel cells are considered the ultimate solution for future clean energy vehicles. However, limited by global reserves and exploitation, the high cost caused by applying noble metal (Pt) in membrane electrode assemblies (MEAs) has become a "bottleneck" for the large-scale promotion of fuel cell vehicles. A continuous reduction in Pt loading will hardly satisfy the requirements of high power output, long life, adaption to extreme operating conditions in various application fields of fuel cells1-3. Herein, the scientific issues concerning both kinetics and mass transfer in ultra-low Pt MEAs are first revealed. Then, the development of highly efficient Pt or non-Pt electrocatalysts for oxygen reduction are introduced. Finally, some innovative solutions dealing with MEAs and flow field are provided. It is believed that this should provide both scientific and technical supports for the development of ultra-low Pt proton exchange membrane fuel cells. Keywords: ultra-low Platinum, membrane electrode assemblies, kinetics and mass transfer, highly efficient Pt or non-Pt electrocatalysts, oxygen reduction reaction, proton exchange membrane fuel cells Reference [1] C. Wang, X.J. Cheng, J.B. Lu, S.Y. Shen, X.H. Yan, J.W. Yin, G.H. Wei and J.L. Zhang, The Journal of Physical Chemistry Letters, 2017, 8, 5848.[2] S.Y. Shen, X.J. Cheng, C. Wang, X.H. Yan, C.C. Ke, J.W. Yin and J.L. Zhang, Physical Chemistry Chemical Physics, 2017, 19, 26221.[3] Z. F. Zheng, L. X. Luo, F. J. Zhu, X. J. Cheng, F. Yang, S. Y. Shen, G. H. Wei, J. L. Zhang, Electrochim. Acta, 2019, 323, 134751. Acknowledgements This work was supported in part by National Natural Science Foundation of China (21975157) and the National Key Research and Development Program of China (2016YFB0101201 and 2016YFB0101312).