1. The QFtp is created in run function of a QThread.
2. Call connectToHost and login.
3. Call get to download a list file from the ftp server. The list file is a text file, every line represents a file's full path on the ftp server.
4. Parse the list file and call get to download files in the list file one by one.

After every QFtp command call, I will wait the command's result. The wait function is as below:
@
bool DoThread::waitFtpCmd(QFtp *ftp, const int waitSeconds)
{
QDateTime dtStart = QDateTime::currentDateTime();

while(true)
{
    qApp->processEvents();

    if (!ftp->hasPendingCommands() &&
        ftp->currentCommand() == QFtp::None)
    {
        if (ftp->error() != QFtp::NoError)
        {
            showInfo("Error", ftp->errorString());
        }
        else
        {
            showInfo("Ftp", "Cmd OK");
        }
        return ftp->error() == QFtp::NoError;
    }

    if (waitSeconds > 0 &&
        dtStart.addSecs(waitSeconds) < QDateTime::currentDateTime())
    {
        qDebug() << "ftp state: " << ftp->state();
        qDebug() << "current cmd: " << ftp->currentCommand();
        qDebug() << "pending cmds: " << ftp->hasPendingCommands();
        showInfo("Error", "Cmd TimeOut");
        break;
    }

    msleep(100);
}//while

return false;

}
@

The problem occurs in the 4th step, after downlaod n files, while n maybe 1, 3 or any other number.
All the file I want to download is the same size. Normally do

You may provide further details and/or code - this would help alot.

!https://lh4.googleusercontent.com/-4TS9exAZjmI/TqtEl6qNvGI/AAAAAAAAA8Y/hp4WbG6ezWI/s800/02-IMG_1953.JPG(Crystal ball)!

(picture taken by Volker at the DevDays)

Perhaps you can show us the relevant sections of your code?