Duobuza copper deposit in Tibet is a large porphyry type of gold-rich copper deposit, and the proven amount of copper resource 'is more than 400 X 104 t. At present, it has not been exploited, and the researches mainly focus on prospecting and geological mineralization, and iittle environmental research has been done. In order to understand the enrichment and migration characteristics of heavy metal elements in mining area before the development of Duobuza copper deposit, the surface soll and sediment of Samalong river bed in Duobuza copper m ining area were collected, the contents and speciations of seven heavy metal elements, including Cu, Pb, Zn, As, Cd, Cr, Hg, were tested； meanwhile, geoaccmulation index method, comprehensive pollution index method and risk assessment code (RAC) method were used to evaluate the enrichment degree and biological activity of heavy metal elements in mining area. The results show that the distributions of most heavy metal elements in surface soll and sediment of Samalong river bed are greatly affected by Duobuza copper deposit, and there s a significant correlation between them. The content of Cu in surface soll of Duobuza copper mining area s especially rich, reaching 21 020. 000X10-6 , which s 50 tmes higher than the level ^ standard in environmental quality standard for soil (GB 15618-1995) ； the comprehensive pollution index s 39. 43, which reaches the heavy pollution level, the geoaccmulation indexes of most samples also reach the very strong pollution level , and the biological activity reaches a moderate risk level , and s easy to migrate and transform , which has a great impact on the environment. The maximum content of Cu in sediment of Samalong river bed s 2 406. 000X10-6 , which s 6 tmes of the level ^ environmental quality standard for soil； the comprehensive pollution index is 38. 13 , the geoaccmulation index also reaches 91. 6% , while t mainly exists in a more stable residual state (accounting for 42. 83%), and RAC value s a low risk level , the migration ability s relatively weak , which has iittle impact on the environment, but the risk cannot be ignored; the content of Cd is not high, which is lower than the level IE environmental quality standard for soil , but t mainly exists in the carbonate bond state in river bed sediment (accounting for 48. 01%) , and the biological activity reaches an extremely high risk level , which has a relative great impact on the environment. The contents of Pb , Zn , As, Cr , Hg s generally low , and the biological activity s weak , which can exist stably in the soil, will not affect the environment basically. [ABSTRACT FROM AUTHOR]