Abstract: For calculating the shielding capability of γ-ray with different energy for Pb shielding floor with different thickness, two models were conceived, then these models were simulated with MCNP program, and the Pb shielding capability was calculated and the conclusion was gained. The results show that the shielding capability of Pb shielding floor with the same thickness to low energy γ-ray is better than to high energy γ-ray, and the shielding capability line descends along with the γ-ray energy goes up. For validating this conclusion, the Pb shielding capability in the conditions of single direction γ-ray source, surface source, isotropy surface source and changing PHYS card were calculated, then the same conclusions were gained.