Abstract: The sensitivity of stress protein as a biomarker was researched in the project. The experiment was initiated using 3d old Grobiocypris rarus larvae according to subchronic toxicity test and run for 5d. Special stress proteins of approximately 54KDa or 94KDa, 67KDa and 40KDa were induced in response to Cu2+ or Zn2+ at the No Observable Effect Concentration, respectively. Compared with the conventional end points such as growth, this assay is a more sensitive and rapid indicator. Therefore, stress protein might be an useful biomarker as an early warning system in risk assessment.