Abstract: In this paper, a series of side hydroxyl-containing nonionic surfactants (nH-550) with different carbon chain lengths were synthesized using methoxy poly(ethylene glycols)-550 and alkylene oxide as raw materials. The molecular structure was characterized by 1 H -NMR and the effect of hydrophobic chain lengths on their surface activity was investigated. Furthermore, the nonionic surfactant was compounded with acrylic resin in the same mass ratio, and was applied to the retanning process of aldoxime goat skin. The results showed that 16H -550 had the lowest critical micelle concentration of 0.079 mmol/L, while 8H -550 had the lowest surface tension of 26.8 mN/m. The study also found that the composite retanning agent containing 8H-550 or 12H-550 had a better penetration effect between the skin fibers, and the thickness of the leather after retanning was significantly increased over 10 % . The mechanical properties of the finished leather have been also improved.