在stackoverflow上回報後，很快地收到了Mike的回覆： https://stackoverflow.com/questions/23368191/compute-engine-use-gsutil-to-download-tgz-file-has-crcmod-error The object you're trying to download is a composite object ( https://developers.google.com/storage/docs/composite-objects ), which basically means it was uploaded in parallel chunks. gsutil automatically does this when uploading objects larger than 150M (a configurable threshold), to provide better performance. Composite objects only have a crc32c checksum (no MD5), so in order to validate data integrity when downloading composite objects, gsutil needs to perform a crc32c checksum. Unfortunately, the libraries distributed with Python don't include a compiled crc32c implementation, so unless you install a compiled crc32c, gsutil will use a non-compiled Python implementation of crc32c that's quite slow. That warning is printed to let you know there's a way to fix that performance problem: Please run: gsutil help crcmod ...