A novel ethoxylated gemini trisiloxane surfactant B whose general formula is of RO(CH 2 CH 2 O) 8.7 R [R = Me 3 SiOSiMe(CH 2 ) 3 · OSiMe 3 ] has been synthesized using polyethylene glycol 400, 3-chloropropylene and 1,1,1,3,5,5,5-heptamethyltrisiloxane as main raw materials. This compound was structurally characterized by ESI-MS, 1 H-NMR and 13 C-NMR spectroscopy. Its surface activity and application properties containing spreading performance and hydrolysis resistance were also measured. The critical aggregation concentration (CAC) and the surface tension of surfactant B solution at CAC (γ CAC ) of are 2.63 × 10 −6 mol L −1 and 20.7 mN m −1 , respectively. This CAC is only one-tenth of the CAC of the Υ-shaped ethoxylated double-tail trisiloxane surfactant 1P , where CAC was replaced with critical micelle concentration (CMC), indicating that surfactant B has an extremely high surface activity. The spreading ability (SA) of its solution (5 × 10 −3 mol L −1 ) within 1 min over Parafilm, PE film and ficus microcarpa leaves is 23.9, 45.7 and 59.8, respectively, suggesting that this surfactant has a better SA than 1P and possesses superspreading. This surfactant also possesses a stronger hydrolysis resistance than 1P ; for instance, in pH 10.0 environment for 86 days. The surface tension of surfactant B solution has been no more than 6 percent of its initial value. It is suggested that the excellent interfacial properties of surfactant B is related to its U-shaped conformation in water.