In　response　to　the　challenges　faced　by　edge　computing　in　terms　of　storage　and　security,　we　design　a　lightweight　and　secure　edge　computing　architecture　based　on　blockchain.　First,　we　conducted　in-depth　research　on　lightweight　communication　protocols,　and　propose　a　lightweight　communication　model　by　combining　Constrained　Application　Protocol　(CoAP)　and　Message　Queuing　Telemetry　Transport　(MQTT).　Second,　in　order　to　ensure　the　security　and　traceability　of　the　data　on　edge　computing　node,　we　propose　a　novel　data　storage　mechanism　based　on　blockchain　and　InterPlanetary　File　System　(IPFS).　Finally,　we　design　an　improved　scheme　of　the　Practical　Byzantine　Fault　Tolerance　(PBFT)　consensus　algorithm　to　improve　the　throughput　of　the　system.　The　results　show　that　the　proposed　edge　computing　architecture　has　the　characteristics　of　strong　robustness　and　low　system　overhead,　which　provides　new　ideas　for　promoting　blockchain-based　edge　computing　to　become　a　key　technology　for　upgrading　Internet　of　Things　(IoT)　services.