On August 16, Xiaomi will formally launch the long-awaited MIUI 6 OS and as of today, users may not enlist to participate in its beta tests.
Xiaomi announced in MIUI’s official Weibo account that users can sign up to participate in beta tests for the MIUI 6 in WeChats from today until the 15th.
Please note that when you register, you have to provide information such as your profile name in the MIUI forum or your Xiaomi account number, your real name, your IMEI number, and a basic introduction of yourself. Xiaomi will select users to participate in the beta tests. Do not miss any important news about the MIUI 6 at this time.
The first batch of phones that Xiaomi will use for beta testing on August 16 includes the China Unicom and China Telecom versions of the Mi 3 and Mi 4. Other phones will be announced later.
Furthermore, users should remember that they will not get the MIUI 6 when it is launched on the 16th as it will only go through beta testing. Open beta testing should start at around September. [source]