Abstract: 1,1,1,3,5,5,5-heptamethyl-3-2-(trimethoxysilyl)ethyl trisiloxane(HTEO) was synthesized by hydrosilylation of vinyltrimethoxysilane (VTMS) and 1,1,1,3,5,5,5-heptamethyltrisiloxane (MDHM) in the presence of Custer catalysts, and the structure of HTEO was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR) respectively. Then two kinds of organosiloxane modified poplar fibers (VPF and HPF) were prepared by surface modification of poplar fibers (PWF) with VTMS and HTEO. The chemical structure and surface properties of PWF before and after modification were investigated by FT-IR, scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectrometer (EDS) and contact angle measurements, respectively. It was shown that the O/C value of the modified poplar fiber decreased, the content of Si increased obviously, and the surface of the fiber became rough. The hygroscopicity of the modified poplar fiber decreased and the hydrophobicity was improved. The Si content of HPF was 5.92%. The crystallinities of VPF and HPF were 72.0% and 75.6%, which increased by 14.8% and 20.6% respectively compared with that of PWF. The contact angles of water droplets on VPF and HPF surfaces after static 480 s were 106° and 134°, respectively.