The　adsorption　of　benzene　on　Cu(100)　was　analyzed　using　the　first-principle　density　functional　theoretical　(DFT)　slab　calculation.　In　three　optimized　adsorption　modes　the　benzene　molecules　were　parallel　to　the　surface　and　the　carbon　rings　were　distorted.　The　calculated　results　showed　that　interaction　between　the　substrate　and　benzene　molecule　was　relatively　strong　chemisorption.　The　hollow　site　was　the　most　favorable　adsorption　site　of　benzene　on　Cu(100)　surface,　followed　by　the　bridge　one.　The　top　site　was　the　least　stable.　The　C-C　bond　was　elongated　in　comparison　with　the　free　benzene　molecule　while　the　variation　of　C-H　length　was　small.　The　hydrogen　atoms　bent　away　from　the　solid　surface,　but　they　bent　toward　the　solid　surface　in　the　top　site.　Electron　transference　was　found　from　benzene　to　Cu　substrate.