Node　identity　authentication　is　an　essential　means　to　ensure　the　security　of　the　Internet　of　Things.　Existing　blockchain-based　IoT　node　authentication　schemes　have　many　problems.　A　heterogeneous　IoT　node　authentication　scheme　based　on　an　improved　hybrid　blockchain　is　proposed.　Firstly,　the　hybrid　blockchain　model　is　designed　to　make　the　blockchain　and　IoT　environment　more　compatible.　Then　the　proxy　node　selection　mechanism　is　intended　to　establish　a　bridge　between　the　ordinary　IoT　node　and　the　blockchain,　building　by　calculating　the　trust　value　between　nodes.　Finally,　based　on　the　improved　hybrid　blockchain,　the　node　authentication　scheme　of　the　model　and　proxy　node　selection　mechanism　establishes　a　secure　connection　for　communication　between　nodes.　Safety　and　performance　analysis　shows　proper　safety　and　performance.