On the basis of world energy and clean environment requirements,hydrogen energy properties and hydrogen energy applications,the reality of hydrogen energy which would be one of the most competent candidates of alternative energy resource and/or the dominant energy in future world energy constituent,has been investigated extensively.With the analysis of hydrogen production,hydrogen storage,hydrogen transfer and fuel cell technological progress,the feasibility of hydrogen energy utilization has been verified powerfully.Three typical fuel cell energy systems are introduced and discussed briefly.Finally,authors believe that transformation of hydrogen economy strongly relys on the fuel cells technological progress and the construction of hydrogen energy infrastructure.