Materials and structures of radio-voltaic/radio-photovoltaic (RV/RPV) dual effect isotope batteries were optimized in this paper. The response relationship between different types of volt layer and the dual effect was studied. The GaAs volt layer with a high band gap can easily obtain a higher voltage output than the Si volt layer. Dual effect multilevel isotope batteries achieved better output performance by using the CsI scintillator due to its high photon yield. The CsI scintillator combined with the GaAs volt layer showed good spectral matching property, which is conducive to improve the RV/RPV dual effect isotope batteries. The overall scale of the multilevel structure was designed by performing Particle and Heavy Ion Transport code System (PHITS) calculation. When its overall scale reached 20 cm, the deposition rate of Co-60 gamma (gamma) rays exceeded 90%. The response relationship between the thickness of each level of the CsI scintillator and the battery performance was analyzed by MCNP5. The total performance came up to the maximum when the CsI thickness in each level reached 2 cm. Finally, the multilevel isotope batteries were prepared. The output performance of the multilevel isotope batteries was characterized under Co-60 gamma source at a dose rate of 0.103 kGy/hr. The multilevel isotope battery in series obtained open circuit voltage of 7.77 V, short circuit current of 1.69 mu A, maximum output power of 7.98 mu W, and energy conversion efficiency of 0.15%. These isotope batteries showed great potential for the power supply of electronic equipment in many special fields.