Abstract: Objective:The stability of Cordyceps militaris yellow pigment A1, included light stability, thermal stability, pH stability, metal ions stability and oxygen tolerance, were studied.Methods:Using high performance liquid chromatography (HPLC) to detect retention rate indicators.Results:Light destroyed the pigment and the affection degree was as follows:sunlight>incandescent>UV light>dark.Good thermal stability at low temperatures except over 60℃.pH stability in the order:acid>neutral>alkaline.Metal ions like Na+, K+, Ca2+ and Mg2+ showed little effect on this pigment.Oxygen had a certain influence on the stability of Cordyceps militaris yellow pigment A1.Conclusion:Extraction and purification of Cordyceps militaris yellow pigment A1 should be conducted in the dark, low temperature, absolute oxygen and also acidic environment.