For　different　distributions　of　the　fiber　bundles　in　matrix　materials,　a　micromechanical　model　was　developed　to　investigate　the　effective　properties　of　the　composites.　The　composites　consist　of　a　solid　matrix　and　fiber　bundles.　It　is　assumed　that　the　composite　has　a　periodic　microstructure　and　the　contact　between　fibers　in　the　fiber　bundle　is　smooth.　The　stiffness　coefficients,　transverse　Young＇s　modulus,　shear　modulus　and　Poisson　ratio　of　the　composites　are　calculated　by　the　two-scale　expansion　method.　The　numerical　results　are　compared　with　the　experimental　data.　It　is　indicated　that　the　distributions　of　the　fiber　bundle　can　directly　affect　the　effective　properties　of　the　composites.