Objective  The selenium contents in rocks, soils and agricultural products in Langao were discussed and their distribution characteristics and relationships were analyzed.

  Method  Samples of rocks, soil and agricultural products in Langao were collected and the total selenium contents in the samples were determined.

  Result  The results showed that the selenium contents in Langao rocks ranged from 0.006 to 43.38 mg kg⁻¹, with an average of 4.15 mg kg⁻¹. The selenium contents in Sinian and Cambrian strata were significantly higher than those in other strata. The selenium contents in soil ranged from 0.00007 to 33.4 mg kg⁻¹, with an average of 0.89 mg kg⁻¹. The percentage of soil enriching selenium was up to 76.08%, and selenium contents in surface soil was obviously higher than that in sub soil. The contents of selenium in crops ranged from 0.0006 to 0.64 mg kg⁻¹, with an average of 0.08 mg kg⁻¹. The order of selenium contents in crops from high to low was other plants (mulberry, toona sinensis), medicinal plants, fruits, tea, grain, konjac and vegetables in turn.

  Conclusion  Selenium in soil showed good inheritance to rock selenium. The order of selenium contents in crops which planted on the same selenium content was from high to low for medicinal plants, fruits, other plants, grain, tea, vegetables and konjac. The average selenium content in crops grown in rich selenium soil was higher than that of in poor selenium soil. vegetables and konjac. The average selenium content in crops grown in rich selenium soil was higher than that of in poor selenium soil.