Abstract: Different patterns of isoenzyme bands are showed in the analysis on different parts of sweetpotato.The isoenzyme bands which from the stem issue between the 9th and 11th blades are clear,complete and stable,and can be used for analysing the affinity among different varieties.We have tested the peroxidase isoenzyme of the stem tissue in 88 sweetpotato varieties.22 bands were found and 8 of them showed more than 90% apparent frequency,which are considered as the typically characteristic bands.The whole varieties were classified into 11 patterns.The varieties among one pattern have the same or similar isoenzyme bands,which revealled their affinity was more close.The affinity between different patterns was analysed by the fuzzy cluster analysis.A52,Jinshan 57 and C180 varieties are divided into seperate patterns.There are bigger gaps between them and other varieties.Maybe there are typical enzyme bands exist in the fine varieties.