Aiming at the main problem encountered in the research of radioisotope microbattery based on β radio-voltaic effect-enhancement of energy transfer efficiency and radiation damage as mutually constraining sides of a contradiction, an investigation of radiation-induced defects in different silicon wafers by low-energy electron irradiation was carried out and the electrical characteristic measurement for two types of PIN structures indicated that P+I (N-) N+ device in I zone with a dopant concentration of 2× 1012 cm-3 agreed with the predicted result of P, N type silicon radiation damage effect. This was then taken as the prototype device, on which test of 63Ni radiation output characteristics was performed. The test result was compared with the experimental data of Wisconsin University and the major factors causing low energy transfer efficiency were analysed. Adoption of three-dimensional PIN junction structure, increasing the proportion of energy deposition in depletion region, matching I (N-) zone width and deposition depth and controlling the leak current under an order of magnitude of Picoampere were considered to enhance the energy transfer efficiency, based on which energy transfer structure was designed and ultimately structure parameters such as multi-hole PIN structure, radiation source thickness, depletion region width were determined, thus the energy transfer structure optimization was accomplished.