在项目的pro文件中添加如下代码：
INCLUDEPATH += D:/opencv/build/include
win32:CONFIG(debug, debug|release): {
LIBS += -LD:/opencv/build/x86/vc12/lib
-lopencv_core249d
-lopencv_imgproc249d
-lopencv_highgui249d
-lopencv_ml249d
-lopencv_video249d
-lopencv_features2d249d
-lopencv_calib3d249d
-lopencv_objdetect249d
-lopencv_contrib249d
-lopencv_legacy249d
-lopencv_flann249d
} else:win32:CONFIG(release, debug|release): {
LIBS += -LD:/opencv/build/x86/vc12/lib
-lopencv_core249
-lopencv_imgproc249
-lopencv_highgui249
-lopencv_ml249
-lopencv_video249
-lopencv_features2d249
-lopencv_calib3d249
-lopencv_objdetect249
-lopencv_contrib249
-lopencv_legacy249
-lopencv_flann249
}
注意：
- LIBS路径要对应Qt使用的VS版本。
- -l链接的都是当前版本下的动态链接库文件名（没有后缀名）。
参考：https://www.librehat.com/qt-5-2-vs2012-opencv-2-4-7-dev-environment-setup-tutorial/