The invention discloses a design method of a positive electrode nitrogen purging strategy of a proton exchange membrane fuel cell. By defining indexes for judging advantages and disadvantages of the purging strategy, a proper and excellent purging strategy is provided for different batteries in different operating conditions. The strategy design comprises selection of three parameters: 1, purgingstarting moment of operation in different current densities; 2, purging flowing rate; and 3, the optimal duration of purging. A cell pile exhausting valve is adopted for positive electrode nitrogen purging, so that energy conversion efficiency of the fuel can be improved while hydrogen emission can be reduced; by making comparison between the energy utilization rate and the fuel waste rate, the excellent property of the purging strategy is judged, wherein the indexes for judging the advantages and disadvantages of the purging strategy comprise the energy utilization rate and the fuel waste rate; by performing purging strategy design on the actual fuel cell working condition, the energy conversion efficiency of the fuel cell can be improved, waste emission of hydrogen fuel can be reduced, and optimization of the nitrogen purging strategy in the positive electrode of the proton exchange membrane fuel cell is realized.