Background: Currently

lead glass is widely used as observation window

while lead is toxic heavy metal. Purpose: Non-toxic materials and their shielding effects are researched in order to find a new material to replace lead containing material. Methods: The mass attenuation coefficients of bismuth silicate glass were investigated with γ-ray’s energy at 0.662 MeV

1.17 MeV and 1.33 MeV

respectively

by MCNP 5(Monte Carlo) and WINXCOM program

and compared with those of the lead glass. Results: With attenuation factor K

shielding and mechanical properties taken into consideration

bismuth glass containing 50% bismuth oxide might be selected as the right material. Dose rate distributions of water phantom were calculated with 2-cm and 10-cm thick glass

respectively

irradiated by 137Cs and 60Co in turn. Conclusion: Results show that the bismuth glass may replace lead glass for radiation shielding with appropriate energy.