The Se content in Trionyx triunguis was studied by atom fluorescence photometer with wet digestion. The recovery of the method is 96.2%-103.0%, relative standard deviation is 3.69%, the determined value of national standard substance pork are agree with standard value; and the method is simple, convenient, fast with good accuracy and precision. The results showed that Se in Trionyx triunguis was very rich, more 1.2-9.4 than Se contant in animal meal, more ten to hundred then it in refresh vegetables and fruits. These results provide a useful scientific base for making and exploiting healtyful foods with Se trionyx triunguis.