Abstract: The Ordos Basin is a basin, which contains the largest amount of gas fields with proved geological reserves over 100 b m^3 in China. It is also the most stable craton petroliferous basin in China. According to the helium isotope analyses for 46 gas samples from the basin, the following results have been obtained： ^3He/^4He values, range from 3.1×10^8～1.2×10^-7, averaging 4.36×10^-8 ; R/Ra values, range from 0. 022 to 0. 085. These data show the character of crust-derived helium. The values of ^3He/^4He and R/Ra show no relation with the formation types, occurrence, autogenetic characteristics and catageneic changes of natural gases in the basin. The values of R/Ra quantitatively demonstrate the extremely stable structure of Ordos Basin.