Abstract: Fuel battery technology is an important way to alleviate energy crisis and environmental pollution problems. As we know, the voltage of single fuel battery is too low to maintain regular service of equipment. In order to realize higher voltage gain function, as well as further adopt security precautions, two kinds of Boost-isolated DC-DC converters(namely Boost-Forward DC-DC converter and Boost-Flyback DC-DC converter) are introduced in this paper. We carry out modeling and simulation analysis of Boost-Forward and Boost-Flyback DC-DC converter with OrCAD Pspice software. Ultimately, the fundamental principle of the design could be proved to be feasible. Moreover, the optimization setting of circuit parameters could also be conducted by reducing the output voltage and input current harmonic, as well as switching voltage stress.