To　explore　the　effect　of　carbon　black　on　the　mechanical　behavior　of　rubber　material,　9　kinds　of　rubbers　filled　with　different　volume　fraction　of　carbon　black　are　studied　by　quasi-static　uniaxial　tensile　test,　and　the　material　constants　of　Mooney　rubber　are　fitted　through　the　least　squares　methods,　then　three-dimensional　numerical　models　containing　multi-sphere　particles　randomly　distributed　are　built　to　simulate　the　mechanical　behavior　of　carbon　black　filled　rubber　composite.　The　research　shows　that　the　stiffness　of　the　rubber　composite　is　increased　considerably　with　the　introduction　of　carbon　black　filler　particles,　and　the　greater　the　carbon　black　filler　content,　the　higher　the　initial　modulus　of　the　rubber　composite,　the　greater　the　strain　energy　density　at　the　same　deformation　condition,　and　the　more　obvious　the　stress　relaxation　phenomenon.　With　7　and　15　percent　carbon　black　filler　content,　the　results　of　the　predictions　on　the　stress-strain　behavior　of　the　rubber　composite　made　with　the　microscopic　numerical　models　are　consistent　well　with　the　macroscopic　test　curves.　With　25　percent　carbon　black　filler　content,　the　results　of　the　predictions　with　the　microscopic　numerical　models　are　slightly　below　the　macroscopic　test　curve.　It　demonstrates　that　the　predictions　on　the　mechanical　behavior　of　carbon　black　filled　rubber　composite　made　by　the　three-dimensional　numerical　model　containing　multi-sphere　particles　randomly　distributed　are　in　good　agreement　with　the　experimental　results,　which　confirms　the　rationality　and　adaptability　of　the　proposed　model,　and　these　researches　provide　the　basic　and　scientific　information　for　further　research.　©　2013　Journal　of　Mechanical　Engineering.