From Visual Studio 2008 Command Prompt I run this command to generate .vcproj file:
>qmake -spec win32-msvc2008
And get a warning message:
WARNING: Generator: MSVC.NET: Found more than one version of Visual Studio
in your path! Fallback to lowest version (MSVC.NET 2008 (9.0),
MSVC.NET 2008 Express Edition (9.0), MSVC.NET 2005 (8.0),
MSVC.NET 2008 (9.0) in path, MSVC.NET 2008 Express Edition (9.0) in path)
For this project I use MSVS 2008 Professional. Actually the generated .vcproj file works well, but what is the warning message about?
I removed all references of the older version of Visual Studio from the PATH environment variable and it now works fine.
On Windows XP: From My Computer -> Properties -> Advanced tab, click on "Environment Variables" button. In both the user and system variables sections, select PATH and click the edit button - copy the text to a text editor (if you want to save your originals) and remove any reference to Visual Studio 2005. Also, make sure your QTDIR and QMAKESPEC variables are set to the version of Qt you want to use.
qmake found 2 Visual Studios, that use the same mkspec (win32-msvc2008).
Try running qmake from corresponding environment (Start->All Programs->Microsoft Visual Studio 2008 [Express]->Visual Studio Tools->Visual Studio 2008 [Express] Command Prompt).
来源：https://stackoverflow.com/questions/1448269/qmake-and-multiple-msvs-versions