Sign in to the Windows Azure Portal and click on the site name in all projects.
Click "Configure".
Select Open in the Remote debugging option, and select 2012 In the remote debugging Visual Studio version.
Click on the "Save" button below.
Come to the VS2012 project and make a breakpoint in the program.
Right-click on the project, press "Publish", select "Debug" in "Configuration" and click "Publish" button.
In Visual Studio 2012, click the "Debug" button, and then click "Attach to Process".
In the "Attach to process" window, in the qualifier, enter the Windows Azure URL, without HTTPS, such as: yourwebsitename.chinacloudsites.cn, tick "show all users of the process."
In the Windows Security window that pops out, you are asked to enter a user name and password.
Go back to the Windows Azure Portal again and click on the site name in all items.
At the bottom right, click Download Publish profile (if you don't need to download it before), save it somewhere on your local computer. Open with Notepad.
Look for Username= and userpwd=, copy its value to the user name and password required in the Windows Security window, and note that you want to precede the username= value with. \, which is the form of the user name:. \someusername, click the "OK" button.
Select the w3wp process and click on the "Attach" button.
Resources:
http://azure.microsoft.com/blog/2014/05/06/introduction-to-remote-debugging-on-azure-web-sites/
Http://blogs.msdn.com/b/webdev/archive/2013/11/05/remote-debugging-a-window-azure-web-site-with-visual-studio-2013.aspx
Remotely debug a Windows Azure Web site by using visual Studio 2012