In this paper, a two-dimensional mathematical model of a processor for fuel cell vehicles was presented in order to predict the effect of the parameters on the hydrogen content of the processor. The structure of the processor and the operating parameters were taken into account in the model. The complex physical and chemical process in the processor of dimethyl ether partial oxidation was well described by this model. The mathematical model was introduced into the commercial software star-cd, and then numerical simulations were also performed based on this model. In order to accounting for the effect of the processor temperature and volume fraction field, TGrid mesh method and laminar flow model were selected. Experimental verification of the two-dimensional mathematical model was implemented on self-designed equipment. The result indicates that the computed data is in good agreement with the experiment one. Finally, on the basis of the mathematical model, the effect of the parameters on the hydrogen content of the processor were investigated.