Abstract: Thick-skin muskmelon varieties ‘Xuetong 8’ and ‘Xuetong 9’ and thin-skin muskmelon varieties ‘Cuiyu 6’ and ‘Zhentian 18’ were used as experimental materials with the method of regeneration of melon cotyledon in vitro.The effects of different hormones and concentration ratio on the regeneration system of melon cotyledon were studied, in order to provide reference for genetic transformation and genetic engineering breeding of melon.The results showed that the optimal disinfection concentration of NaClO solution was 0.2% for melon seeds, and the cell kinin 6-BA and auxin IAA or NAA were added into MS medium to induce the cluster buds of melon cotyledons.There were significant differences in bud differentiation between thick-skin melon and thin-skin melon.The optimal medium for bud differentiation of ‘Xuetong 8’ and ‘Xuetong 9’ was MS+1 mg·L^-1 6-BA+0.1 mg·L^-1 IAA,and the bud differentiation rate was 90.3% and 88.9% respectively.While the optimal medium for bud differentiation of ‘Cuiyu 6’ and ‘Zhentian 18’ was MS+2 mg·L^-1 6-BA+0.3 mg·L^-1 IAA,and the bud differentiation rate was 85.5% and 91.7% respectively.The best medium of bud elongation for thick-skin melon and thin-skin melon was the same which was MS+0.2 mg·L^-1 KT,and the shoots elongated quickly and geminated well.The best rooting medium was 1/2MS+0.1 mg·L^-1 IAA,and the roots grew quickly and strong.