Lemon peel pectin was extracted by papain,followed by alcohol precipitation,and the optimal condition was investigated. The effects of papain concentration,temperature,liquid-solid ratio,pH and extraction time were studied. The extraction technology was optimized by orthogonal experimentation on the basis of a series of singlefactor experiments. The optimal conditions of extraction were obtained as follows: the amount of 0. 10 % papain,liquid-solid ratio 25∶ 1,pH 7,temperature 55 ℃,extraction time 2 h. Pectin yield could reach 32. 3 % under the best conditions.