In　recent　years,　a　variety　of　image　encryption　methods　based　on　chaotic　systems　has　been　proposed,　and　has　achieved　good　results.　In　order　to　improve　the　security　of　image　encryption,　this　paper　proposes　a　new　image　encryption　method　with　a　dynamic　key,　based　on　a　hyperchaotic　system　and　the　association　of　pixel　information,　and　designs　the　three-level　encryption　structure　with　diffusion　encryption,　scrambling　encryption　and　re-diffusion　encryption.　The　innovation　of　this　method　is　to　add　the　whole　information　of　the　image　and　the　position　information　of　the　pixels　in　the　diffusion　encryption,　and　add　the　data　information　of　the　pixels　in　the　scrambling　encryption.　The　plaintext　information　of　the　image　is　added　to　the　encryption　process,　which　can　enhance　the　security　of　encryption.　Experiments　demonstrate　that　the　image　encryption　method　proposed　in　this　paper　has　the　characteristics　of　strong　sensitivity,　low　correlation　between　adjacent　pixels,　anti-differential　attack　and　high　security.　Copyright　©　2018　Inderscience　Enterprises　Ltd.