Background:　Because　of　the　damage　induced　by　ionizing　radiation,　bipolar　transistors　in　integrated　voltage　regulator　could　induce　the　current　gain　degradation　and　increase　leakage　current.　This　will　bring　serious　problems　to　electronic　system.　Purpose:　In　order　to　ensure　the　reliability　of　the　device　work　in　the　radiation　environments,　the　device　irradiation　reinforcement　technology　is　used.　Methods:　The　characteristics　of　60Co　γ　irradiation　and　annealing　at　different　temperatures　in　bipolar　transistors　and　voltage　regulators　(JW117)　with　different　passive　films　for　SiO2+BPSG+SiO2　and　SiO2+SiN　have　been　investigated.　Results:　The　devices　with　BPSG　film　enhanced　radiation　tolerance　significantly.　Because　BPSG　films　have　better　absorption　for　Na+　in　SiO2　layer,　the　surface　recombination　rate　of　base　region　in　a　bipolar　transistor　and　the　excess　base　current　have　been　reduced.　It　may　be　the　main　reason　for　BJT　with　BPSG　film　having　a　good　radiation　hardness.　And　annealing　experiments　at　different　temperatures　after　irradiation　ensure　the　reliability　of　the　devices　with　BPSG　films.　Conclusions:　A　method　of　improving　the　ionizing　irradiation　hardness　of　bipolar　transistors　is　proposed.　As　well　as　the　linear　integrated　circuits　which　containing　bipolar　transistors,　an　experimental　basis　for　the　anti-ionizing　radiation　effects　of　bipolar　transistors　is　provided.