注意将label加入到pictureBox的Controls属性中,而不是Form的。如:
Label label = new Label();
label.Text = "kkk";
label.Location = new Point(10, 10);
label.BackColor = Color.Transparent;
label.ForeColor = Color.Blue;
pictureBox1.Controls.Add(label);
label.BringToFront()
带到前面来