Abstract: Purple potato and purple sweet potato exhibited similar colors. According to the national standard， the nutrient composition including water， starch， protein， fat， reducing sugar， dry matter， mineral elements， pigment， vitamin， amino acids were compared between purple potato and purple sweet potato， using atomic absorption spectrophotometry， and amino acid analysis. It was shown that the contents of reducing sugar， dry matter， Zn， and pigments such as cyanidin， peonin and β\|carotene in purple sweet potato were significantly （P<001） higher than that in purple potato， while， the starch content in purple potato was significantly （P<001） higher than that in purple sweet potato. The contents of total amino acids， essential amino acids， non\|essential amino acids， sweet amino acids and bitter amino acids in purple sweet potato were significantly （P<001） higher than that in purple potato. But， the ratio coefficient of amino acids was more concentrated in purple potato， along with a higher score of ratio coefficient of amino acids.

Key words: purple potato, purple sweet potato, nutrient composition