Abstract: The experimental parameters were investigated in Agrobacteraum—mediated tranformation of melon cotyledons based on the transient expression rate of GUS gene．The result showed that melon cotyledons had lligh tolerance to Kanamyein with concentration of 150 mg／L, which was used to screen the cotyledon ofmelon after transformation．Addition of Ag+ into cocultivation medium was more beneficial for improving transformation frequency，however，acetosyringone (AS) was useless．The different disinfection methods should be taken according to different seasons for saving the melon seeds．

Key words: melon, agrobacterium tumfaciens, genetic transformation, gus transient expression