Aiming at the heavy calculation load existing in the solution to the shortest path in urban road networks,this paper proposes a parallel genetic algorithm based on MapReduce in light of analysis of the features and short-comings of genetic algorithm,and has validated the effectiveness of this algorithm based on Changchun City's dataof road network features.Experimental results show that the proposed algorithm based on MapReduce is of fasterconvergence rate and shorter running time in comparison with the traditional genetic one; and that the inter- nodecommunication load increases as parallel nodes increase,so that proper selection of node number plays a key role inenhancing the operation efficiency.