Abstract: Wood plastic composites (WPC) made from Chinese white poplar (Populus tomentosa) and Canacian poplar (Populus canadensis) were studied. 1. Styrene containing a small amount of cis-polybutadiene, divinyl benzene, benzoyl peroxide, tert-butyl perbenzoate and hydroquinone was used as an impregnating liquid for preparing WPC. This impregnating liquid with rather long pot life could be polymerized in higher conversion. The properties of hardness, abrasive resistance, impact strength, static bending strength and dimensional stability of WPC prepared with this impregnating liquid were improved significantly, and increased with inereasing the polymer content in WPC. 2. The temperatures at centers of wood samples against polymeriztion temperatures, amount of initiators, dimensions of wood samples, antioxidants, U. V. stabilizer and time of polymerization were determined. From these, some better control of this kind of polymerization was proposed. 3. The influence on the properties of WPC prepared by the addition of an oil soluble surfactant——ОП—10, or a surface treating agent——toluene diisocyanate in this impregnating liquid was studied. It was found by scanning electron microscope, that the polymer was better distributed in WPC prepared by the impregnating liquid containing a small amount of ОП—10 than that without it, but the bonding properties between polymer and wood cells were still not tight enough.