Objective To study the effect of the tissue components purified from earthworm on the thioredoxin system and its pharmcological mechanism. MethodsAcetate buffer purified the tissue components from the earthworm. The catalyzing activity of the thioredoxin reductases was dynamically measured on the 340nm wavelengthby the NADPH, an indicator by means of the reaction between the tissue components and thioredoxin system. ResultsThe absorbency of the NADPH was almost unchanged in the process of the reaction between the purified tissue components of earthworm and the thioredoxin reductase. On the contrary, the solvent to purify earthworm liquid and the clear liquid from boiled purified earthworm liquid had not above mentioned function. ConclusionsThere are some kinds of proteins in the tissue components of the earthworm, which could inhibit the activity of the thioredoxin reductase.