To screen the varieties(lines) of muskmelon with low potassium tolerance and explore the potential of muskmelon to absorb and utilize potassium by itself,45 different genotypes were collected from Henan main cultivars,and the differences and correlation of the main agronomic characters of muskmelon in seedling stage were analyzed with hole tray and substrate cultivation in phytotron(The suitable and low potassium concentrations were 2.50 mmol/L and 0.01 mmol/L,respectively),to select muskmelon varieties(lines)with low potassium tolerance by principal component analysis and membership function method.The results showed that the variation coefficients of 11 agronomic traits of 45 cultivars(lines) were large under the conditions of suitable potassium and low potassium, and all the variation coefficients reached more than 10.0%,except for SPAD value and stem diameter at the level of suitable potassium.The principal component analysis method reduced the dimension of the original 11 agronomic characters and extracted 3 principal components,reflecting 62.338% of the original information.The load values of K accumulation,plant height,plant biomass,total root absorption area and root volume were higher in the first principal component, SPAD value and leaf area were higher in the second principal component, and stem size,root activity and K utilization index were higher in the third principal component. 45 melon varieties(lines) were divided into four types by clustering analysis method,typeⅠhad resistance to low potassium,type Ⅱ had medium resistance to low potassium and type Ⅲ was weakly sensitive varieties(lines) to low potassium,type Ⅳ was low potassium sensitive varieties(lines).17 varieties(lines)with low potassium tolerance were preliminarily screened,such as Jangjunyu,Jinxiu,Xuemi,IVF168,Fengmi 29,Yinmi 58 and so on.T120 was selected as low potassium sensitive cultivar(line).