Spin　injection　efficiency　in　the　ferromagnet/　organic　semiconductors　system　(FM/OSEs)　was　explored　considering　the　spin　dependence　of　the　electric-conductivity　induced　by　spin　injection　in　the　OSEs.　It　is　known　that　the　OSEs　is　spin　polarized,　once　spin　was　injected　from　FM　layer　to　OSEs　layer.　The　up-spin　polarons　and　the　down-spin　polarons　have　different　density.　The　spin　dependence　of　the　electric-conductivity　is　so　induced.　In　the　literature,　it　was　usually　supposed　that　the　electric-conductivity　in　the　spin　polarized　OSEs　is　spin　independent.　So,　it　is　crucial　to　reflect　the　physics　in　the　spin　injection.　Our　work　shows　that　the　spin-dependent　electrical-conductivity　is　one　of　the　significant　factors　which　affect　the　spin　injection　efficiency.　The　spin　injection　efficiency　increases　obviously　with　the　rising　of　the　spin-dependent　electrical-conductivity　in　the　same　spin　injection　system.　And　the　effect　becomes　larger,　when　the　polaron　proportion　increases.　Furthermore,　the　effects　of　interfacial　electrochemical-potential　proportion　on　the　spin　injection　efficiency　in　the　heterojunction　are　also　included.