[en] The methods and results of the investigation on natural penetrating radiation level in Yunnan Province are presented. 630 25 km x 25 km-grid measuring points were set up uniformly all over the province, with 955 densely measuring points of different types added. The results show that :(1) The area-weighted, population-weighted and point-weighted average value of natural γ radiation dose rate for field is 66.0, 64.8 and 66.7 nGy·h^-1, respectively; (2) The point-weighted average value of natural γ radiation dose rate for road is 63.2 nGy·h^-1; (3) The population-weighted average and point-weighted value of natural γ radiation dose rate inside building is 91.4 and 93.1 nGy·h^-1, respectively; (4) The point-weighted and population-weighted average value of the dose rate inside buildings from cosmic ray is 40.6 and 39.9 nGy·h^-1, and outside buildings is 45.6 and 45.1 nGy·h^-1, respectively; (5) The point-weighted and population-weighted average value of natural penetrating radiation dose rate inside buildings is 133.7 and 131.3 nGy·h^-1, outside buildings is 112.3 and 109.7 nGy·h^-1, respectively; (6) The annual effective dose equivalent from natural γ radiation, cosmic ray and natural penetrating radiation is 0.51, 0.36 and 0.88 mSv, respectively; and correspondingly, the annual collective effective dose equivalent is 1.7, 1.2 and 2.9 x 10⁴ man·Sv, respectively