Based on allylation of hydroxyl-terminated PEG and hydrosilylation of the allylic double bonds, two kind of linear-dendritic amphiphilic block copolymers with carbosilane hydrophobic head groups attached to PEG hydrophilic bridging chain were synthesized. The molecular structures of the copolymers were characterized with NMR and FTIR, and their surface properties were evaluated. The two copolymers showed good surface activities, and the CAC values are 5.13?0-4 and 4.83?0-5 mol?L-1，γCAC values are 32.48 and 32.21 mN?m-1 respectively. Moreover, two breaks were observed in the surface tension vs concentration curve for the two copolymers, which is believed to originate from rearrangement of the copolymer molecules on the air/water surface, and the molecular architecture of the copolymers at the surface layer were effected by the PEG segments and carbosilane branched blocks of the copolymers.