1. 错误描述
   静态编译了QT库后，我的应用程序要链接到这些静态库。但是出现了如图所示错误：
   
   运行时错误错误提示：
   This application failed to start because it could not find or load the Qt platform plugin "windows" in "".

2. 解决过程
   Google关键字“Qt staticPlugins”, to get the first result as:

How to Create Qt Plugins

To link plugins statically, you need to add the required plugins to your build using QTPLUGIN.

In the .pro file for your application, you need the following entry:

QTPLUGIN += qjpeg \
qgif \
qkrcodecs
qmake automatically adds the plugins to QTPLUGIN that are typically needed by the Qt modules used (see QT), while more specialized plugins need to be added manually. The default list of automatically added plugins can be overridden per type. For example, to link the minimal plugin instead of the default Qt platform adaptation plugin, use:

QTPLUGIN.platforms = qminimal
If you want neither the default, nor the minimal QPA plugin to be linked automatically, use:

QTPLUGIN.platforms = -
The defaults are tuned towards an optimal out-of-the-box experience, but may unnecessarily bloat the application. It is recommended to inspect the linker command line built by qmake and eliminate unnecessary plugins.

Details of Linking Static Plugins
To cause static plugins actually being linked and instantiated, Q_IMPORT_PLUGIN() macros are also needed in application code, but those are automatically generated by qmake and added to your application project.

If you do not want all plugins added to QTPLUGIN to be automatically linked, remove import_plugins from the CONFIG variable:

CONFIG -= import_plugins
Creating Static Plugins
It is also possible to create your own static plugins, by following these steps:

Add CONFIG += static to your plugin's .pro file.
Use the Q_IMPORT_PLUGIN() macro in your application.
Use the Q_INIT_RESOURCE() macro in your application if the plugin ships qrc files.
Link your application with your plugin library using LIBS in the .pro file.
See the Plug & Paint example and the associated Basic Tools plugin for details on how to do this.

Note: If you are not using qmake to build your plugin you need to make sure that the QT_STATICPLUGIN preprocessor macro is defined.

3. 解决方法
上述方法均可以使用。我的项目是VC项目，最直接的办法是在main 文件中全局位置调用宏

// link to static QT lib, following lines to import platform static lib's header
#include
Q_IMPORT_PLUGIN(QWindowsIntegrationPlugin)