In recent years a high attention has been conducted to the structural application of wood plastic composites (WPCs). Regarding that the WPCs have lower mechanical strengths, fiber reinforcements have been applied for strengthening the WPCs. Hybrid wood plastic composites (HWPCs) include two types of reinforcements of glass fibers and wood flours that are added to a polymeric matrix. WPC pallets as an example can exploit the mechanical strength of HWPCs. In previous work, wood plastic composite was reinforced by continuous glass fibers by a unique extrusion process. Embedding the continuous glass fibers in WPC matrix resulted in significant improvements in mechanical properties such as tensile and impact strengths. In this paper, a model has been proposed to predict the tensile strength and modulus of the WPCs reinforced with unidirectional glass fibers. The methodology applied in this research considers the WPC as matrix and the glass fibers as reinforcements. Since WPC matrix is brittle, the rule of mixtures corresponding to the brittle matrix composites was used to predict the tensile strength. Results indicated that the predicted tensile properties were in good agreement with experimental data. The obtained mean errors between the experimental and theoretical results for tensile strength and modulus were 9.5% and 8.6% respectively.