A series of multifunctional UV-curable polysiloxanepolyether block polyurethane acrylates prepolymers (TSi(1)E(9)PUA, TSi(3)E(7)PUA, TSi(5)E(5)PUA, TSi(7)E(3)PUA, and TSi(9)E(1)PUA) used for polyvinyl chloride (PVC) leather finishing agents have been prepared and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and gel permeation chromatography (GPC). All five multifunctional prepolymers exhibited excellent photopolymerization efficiency and good yellowing resistance. And the content of polysiloxane in prepolymers obviously affected the viscosity, thermal stability, tensile strength, elongation at break, and surface hydrophobicity of the photopolymerization systems. The system with the prepolymer containing more polysiloxane segments presented a high viscosity, and UV-cured film had relatively good thermal stability, elongation at break, and surface hydrophobicity accordingly. The properties of the prepolymers well satisfied the application requirements for leather finishing agents. Furthermore, surface microstructures of UV-cured films were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). More importantly, the PVC leather finishing agents designed based on the multifunctional polysiloxanepolyether block polyurethane acrylates possessed excellent comprehensive performances.