foreach (string d in arr)
{
    int index = lv.Items.Count + 1;
    item = new ListViewItem(new string[] { index.ToString(), d, "", "", "", "" });
    lv.Items.Add(item);
    float progress = 0;
    Rectangle SizeR = default(Rectangle);
    System.Windows.Forms.ProgressBar ProgBar = new System.Windows.Forms.ProgressBar();
    SizeR = item.SubItems[2].Bounds;
    SizeR.Width = lv.Columns[2].Width;
    ProgBar.Parent = lv;
    ProgBar.SetBounds(SizeR.X, SizeR.Y, SizeR.Width, SizeR.Height);
    ProgBar.Value = (int)progress;
    ProgBar.Visible = true;
    //取一个唯一的名字，以后好找
    ProgBar.Name = d + "progressbar";
}

//循环listview上的所有控件，按名字找到progressbar
foreach (Control item in lv.Controls)
{
    if (item.Name == d.Name + "progressbar")
    {
      ProgressBar bar = (ProgressBar)item;
      bar.Value = (int)((d.Progress) * 100);
    }
}

private void lvt_ColumnWidthChanging(object sender, ColumnWidthChangingEventArgs e)
{
  Rectangle SizeR = default(Rectangle);
  int width = e.NewWidth;
  foreach (Control item in lv.Controls)
  {
    //根据名字找到所有的progressbar
    if (item.Name.IndexOf("progressbar") >= 0)
    {
      ProgressBar bar = (ProgressBar)item;
      //Rectangle size=bar.Bounds;
      SizeR=bar.Bounds;
      //lv.Columns[2]是放置progressbar的地方
      SizeR.Width=lv.Columns[2].Width;
      bar.SetBounds(lv.Items[0].SubItems[2].Bounds.X, SizeR.Y, SizeR.Width, SizeR.Height);
      //bar.Width = width;
    }
  }
}