Abstract: Due to measuring the background value of specific activity of radionuclides (²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K), 48 collected samples of bottom ash of coal in the coalfields were analyzed by Gamma-ray spectrometer at China Nuclear Radiation Protection Research Institute. The results show that the specific activity are 104.4 Bq/kg (²³⁸U), 37.6 Bq/kg (²³²Th), 126.7 Bq/kg (²²⁶Ra) and 101.7 Bq/kg (⁴⁰K). The enrichment factors(EF) of the radionuclides in bottom ash relative to the input coal during the combustion process range from 0.1 to 26.6 for ²³⁸U, from 3.3 to 309.2 for ²³²Th, from 0.4 to 284.0 for ²²⁶Ra and from 1.7 to 225.5 for ⁴⁰K, whereas the relative enrichment factors(REF) are 0.01 to 19.97 (²³⁸U), 0.06 to 77.9 (²³²Th) and 0.02 to 54.5 (²²⁶Ra). The specific activity of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K present the lowest in bottom ash in Ili Valley of Xinjiang compared with other areas and nations.