How to deploy my application using Qt-Creator?
You also need to deploy the MINGW runtime dll (mingwm10.dll). This file is located in your Qt\2009.5\mingw\bin directory.
Also pay attention to whether your application is compiled in debug mode or release mode. I just made the test with an hello world type application and Qt Creator. In the debug folders, I copied libgcc_s_dw2-1.dll, mingwm10.dll, QtCored4.dll and QtGuid4.dll and it works.
Pay attention to the d in dll names, which stands for debug: QtCore d 4.dll.
See Qt 4.6: Deploying an Application in Windows.For Qt 5, check this page.
If you don't want to have dependencies with qt/mingw dlls you should compile qt statically as explain here: http://qt.nokia.com/doc/4.6/deployment-windows.html#static-linking.
You may also use static linking, just add this line into the .pro file:
QMAKE_LFLAGS += -static-libgcc
I found the solution here and successfully tested on WinXP with QT creator 2.2.0