deepin 15.4 GNU/Linux operating system has been released at April 19th 2017. I list here one official download link and two faster mirrors from Sourceforge. I listed here the Mega and Google mirrors as well but remember they don't provide direct download. The 15.4 provided only as 64 bit, the 32 bit version has already dropped (except by commercial support). I hope this short list helps you.
- Official download link: http://cdimage.deepin.com/releases/15.4/deepin-15.4-amd64.iso
- Mirror 1 (Sourceforge, NCU): https://ncu.dl.sourceforge.net/project/deepin/15.4/Release/deepin-15.4-amd64.iso
- Mirror 2 (Sourceforge, NCHC): https://nchc.dl.sourceforge.net/project/deepin/15.4/Release/deepin-15.4-amd64.iso
- Mirror 2 (Mega, no-direct-link): https://mega.nz/#F!8wtEXCDB!_W8Hd_lTI4o6i29Fljeglw
- Mirror 3 (Google, no-direct-link): https://drive.google.com/drive/folders/0B6tQiyXN9eI9a01mX3ZZT2tXVlk
- Size: 2.6GB
- Checksum: MD5SUM
Note: at this time (April 20th) I cannot find any active ISO mirror (that provides direct link) available for 15.4. If you want to help deepin distribution, you can provide a deepin ISO mirror by following this guide.