Abstract: A method for preparing ~(75)Se--L--Selenomethionine)(NaBH_4 method) is intro-duced which can allow a large batch of ~(75)Se--L--Selenomethionine be preparedthrough manipulator opearation. The total yield of ~(75)Se--L--methionine is 20--30%.The quality of this product is identifed in according to the standards of theInternational Pharmacopoeia, 1974 edition. This product has a radiochemical purityof more than 95%, and has good stability. Tissue distributions in mice show thatthe highest uptake in the pancreas teachs 6--10%, which is in accord with thepublished values. Toxicity test shows that this product is safe for human use.