Wood plastic composites attract great attention in various applications. Chemical modification of the wood fiber with NaOH and various coupling agents was performed for wood fiber composites. Wood fibers treated with NaOH, APTES, TEVS, and BC coupling agents were compounded with PP matrix for measuring physical properties. All those chemical treatments increased physical properties much compared to the untreated case because of the elimination of impurities by NaOH treatment and because of the introduction of compatible molecular structure onto the wood fiber surfaces. Especially, the TEVS case showed the best tensile strength, and it could be attributed to the chain structure having double bond of the molecules for high compatibility with PP matrix. The SEM morphology also demonstrated increased adhesion between wood fibers and PP matrix with chemical treatments. The adhesion between wood fiber and PP matrix would be a key parameter in achieving high physical properties of the composite materials.