Long-life electronic products need to be put in stress environment for long durations in traditional ESS(environmental stress screening) tests in order that items having infant mortality or defects are weeded out from products. However, long stress durations cause aging effects on good items. For some products, failures are defined in terms of performance characteristics degrading some critical values. For the purpose of reducing durations and aging effects, this paper analyzes the difference of performance characteristics between normally degraded products and abnormally degraded products, and assumes the distribution of products’ degradation characteristic variable is contaminated distribution model, then presents a degradation screening test design. This design firstly ascertains the model coefficient using identifiable condition of contaminated distribution combined with the analysis of degradation test, then ascertains screen duration and screen critical value. Lastly, this paper gives an example to illustrate the availability of the design.