1.对pro进行配置，使其能够理解opencv。

INCLUDEPATH+=d:\opencv249\include\opencv                    d:\opencv249\include\opencv2                    d:\opencv249\include

LIBS+=d:\opencv249\lib\libopencv_calib3d249.dll.a        d:\opencv249\lib\libopencv_contrib249.dll.a        d:\opencv249\lib\libopencv_core249.dll.a        d:\opencv249\lib\libopencv_features2d249.dll.a        d:\opencv249\lib\libopencv_flann249.dll.a        d:\opencv249\lib\libopencv_gpu249.dll.a        d:\opencv249\lib\libopencv_highgui249.dll.a        d:\opencv249\lib\libopencv_imgproc249.dll.a        d:\opencv249\lib\libopencv_legacy249.dll.a        d:\opencv249\lib\libopencv_ml249.dll.a        d:\opencv249\lib\libopencv_objdetect249.dll.a        d:\opencv249\lib\libopencv_video249.dll.a

3.配置其.h文件、.cpp文件。

.h文件：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    cv::Mat image;
      QImage img;

private slots:
    void on_pushButton_clicked();

    void on_pushButton_2_clicked();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QString>
#include <QFileDialog>
#include <QMessageBox>
#include <opencv/cv.h>
#include <QTextCodec>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    QString filename = QFileDialog::getOpenFileName(this,tr("Open Image"),"",tr("Image File(*.bmp *.jpg *.jpeg *.png)"));
       QTextCodec *code = QTextCodec::codecForName("gb18030");
       std::string name = code->fromUnicode(filename).data();
       image = cv::imread(name);
       if(!image.data)
       {
           QMessageBox msgBox;
           msgBox.setText(tr("image data is null"));
           msgBox.exec();
       }
       else
       {
           cv::cvtColor(image,image,CV_BGR2RGB);
           img = QImage((const unsigned char*)(image.data),image.cols,image.rows, image.cols*image.channels(),  QImage::Format_RGB888);
           ui->label->clear();
           ui->label->setPixmap(QPixmap::fromImage(img));
           //ui->processPushButton->setEnabled(true);
           ui->label->resize(ui->label->pixmap()->size());
       }
}

void MainWindow::on_pushButton_2_clicked()
{
    cv::flip(image,image,1);
       img = QImage((const unsigned char*)(image.data),image.cols,image.rows,image.cols*image.channels(),  QImage::Format_RGB888);
       ui->label->setPixmap(QPixmap::fromImage(img));
}

补充：

image.cols*image.channels()

1.使用Qt显示openCV矩阵图片    http://blog.csdn.net/homechao/article/details/8989641

2. Qt中用QLabel显示OpenCV中Mat图像数据出现扭曲现象的解决    http://lovelittlebean.blog.163.com/blog/static/11658218620125208212189/