Abstract: In this paper,the ultrasonic assisted extraction of anthocyanin from purple potato was optimized by response surface methodology(RSM). The separation and purification of anthocyanin from purple potato and its stability under different environmental conditions were studied. The results showed that the optimum extraction conditions were as follows:Extraction power 300 W,ratio of material to liquid 1:50 g/mL,extraction temperature 50 ℃,extraction time 15 min,and extraction amount(1.435±0.27) mg/g.Using AB-8 resin,the amount of sample was 9 BV,eluted with 60% ethanol solution of 6 BV,the speed of sample loading and elution was 2.0 mL/min,and the concentration of purple potato anthocyanins in the purified extract reached(6.43±0.37) mg/mL. The results of stability study demonstrated that,the stability of anthocyanin of purple potato was poor under the condition of 245 nm short wave ultraviolet and indoor scattering light,and stable under the condition of avoiding light. The stability decreased with the increasing of temperature under the condition of heating,and was not stable at 90 ℃;it was stable in the solution containing Al³⁺,Mg^2＋,K^＋,Ca^2＋,Na^＋,Zn^2＋,and precipitated in the solution containing Cu²⁺. Purple potato anthocyanins were stable in an acid environment and easy to decompose in an alkaline environment. Therefore,anthocyanins of purple potato should be stored or used in the acid environment of dark,cold storage or normal temperature. The optimized extraction process of anthocyanin from purple potato was reasonable and feasible,and the extracted anthocyanin product had high stability,which could be used as a healthy food colorant or functional component in the food production and development process.