Yield,color scale,purification,stabilization of betalain were tested in the experiment.The results showed that at the pH 3,temperature 70℃,the leaching rate and yield of betalain were the highest,A value was the maximum.When it was maintained at 80℃-90℃ for 3 to 5 minutes,viability of polyphenol oxidase was suppressed effectively.Results of experiments with different extraction method showed that the effect of multi-stage sequential extraction was better.