Embedded　system　security　issues　are　increasingly　prominent,　trusted　computing　is　a　useful　solution.　This　paper　proposes　a　mechanism　to　measure　the　integrity　of　bootloader　and　OS　image　on　Nios　II　based　FPGA　embedded　system.　When　the　system　is　powered　up,　the　bootloader　and　OS　image　is　measured　individually,　and　the　startup　process　depends　on　the　results,　to　ensure　the　whole　startup　process　is　trusted.　The　mechanism　could　be　easily　deployed　on　Nios　II　embedded　system,　there＇s　no　need　to　modify　the　hardware,　it＇s　only　need　to　modify　the　configuration　files　and　download　to　FPGA.　The　integrity　measuring　mechanism　is　helpful　to　the　improvement　of　embedded　systems＇　security.　©　2012　Springer-Verlag　GmbH.