BCRT (Biologically Conformal Radiotherapy) is a hotspot in modern radiotherapy research. The implementation of BCRT concept is based on the rich knowledge on the radio-sensitivity of the cells in target. Monte Carlo method can simulate the radiation damage process economically, and output the rigorous, numeric and microcosmic damage yields. The work calculated the variation of DNA damage yields with energy of irradiation electrons using Monte Carlo codes, MCDS/MCER/VC. The results show that it is easier for the low energy electrons to damage DNA by DSB (double-strand break). The enzymatic DSB has been calculated in the base of the combination of MCDS and MCER, which show that the influence of incident electron energy variation on enzymatic DSB yield is very little, but that of different base excision repair mechanism is notable. The damage yields of 5 β-emitter radionuclides (Lu-177, Cu-67, Re-186, Re-188, and Y-90) have been deduced by weighted energy spectra, which show the Lu-177, Cu-67 with a bit lower energy than the others have a little higher DSB damage yield and lower SSB, OTHER and ALL yields. It also shows that the influence of these 5 radionuclides on DSB yield is relatively the more, but on SSB yield is relatively the less. The cell surviving fraction and the key parameters for two models have been obtained by VC code based on measured data, on which the influence of the repairing time on surviving fraction has been studied.