Abstract: A method of indirect agglut inatio n of red cell w as established , by w hich antibody in sof t-shelled turtle , Triony x sinensis , w as detected .It demonst rated that the highest titer could be obtained w hile the concent ration of sensitizing antigen w as 3 ×108cfu/mL for bacteria and 2 .0mg/mL for BSA , and that of sensitizing red cell of man or sheep w as 2 .5 %.There was no sig nificant dif ferences w ithin 80d in the result s of detecting w ith sensitive red cell , to w hich stabilizer w as added .Furthermore , the sensitivity of this method w as higher , and the method also better in accuracy , specifici ty and duplici ty .