It　is　particularly　important　to　make　quality　evaluation　for　paint　spraying　process.　This　work　presented　an　effi-cient　method　based　on　wavelet　packet　energy　for　terahertz　non-destructive　evaluation　of　organic　protective　paint.　The　wavelet　packet　energy　analysis　algorithm　was　summarized.　Various　coating　structures　were　experi-mentally　investigated　using　terahertz　pulsed　imaging　system　and　the　relative　wavelet　energy　and　the　Shannon　entropy　of　the　detected　signal　were　calculated　as　wavelet　energy　indexes.　The　proposed　algorithm　was　performed　on　the　evaluation　of　coating　unevenness　and　the　identification　of　hidden　corrosion　defect.　The　results　demon-strated　that　the　wavelet　energy　indexes　are　sensitive　to　coating　structure　change　when　compared　to　the　terahertz　peak-finding　method,　and　it　allowed　more　accurate　estimate　of　micro　corrosion　defect.　Therefore,　the　proposed　approach　based　on　wavelet　packet　energy　could　be　recommended　for　quick　quality　evaluation　of　organic　coating　with　terahertz　non-destructive　technology.