Abstract: Graphene betavoltaic isotope battery is one of the applications of graphene in semiconductor and microelectronics. Among them, the modification of graphene is an important research content to improve the application of graphene in these fields. In this study, we compared the effect of nitric acid doping and electron beam irradiation on the output performance of graphene betavoltaic isotope batteries. At the same time, the mechanism of two different methods on the modification of graphene materials was studied by means of light microscope, XPS and Raman spectroscopy. The results show that the nitric acid doping was a surface charge transfer process, which can not change the sp² hybrid carbon atoms in graphene into sp³ hybrid, but can improve the short-circuit current of graphene betavoltaic isotope batteries. While the electron beam irradiation of graphene will introduce defects in graphene, and transform sp² hybrid carbon atoms in graphene into sp³ hybrids, thus opening the band gap of graphene and improving the open circuit voltage and filling factor of graphene betavoltaic isotope batteries. The above results can provide experimental theoretical basis for the design and preparation of graphene betavoltaic isotope batteries, and provide reference for further improving the performance of graphene betavoltaic isotope batteries.