稍加修改就实现了。 
// Set string format.
            StringFormat newStringFormat = new StringFormat();
            newStringFormat.FormatFlags = StringFormatFlags.DirectionVertical;            // Measure string.
            SizeF layoutArea = new SizeF(100, 300);
            SizeF sizeF = e.Graphics.MeasureString(measureString, stringFont, layoutArea, newStringFormat);            // Draw rectangle representing size of string.
            Rectangle layoutRectangle = new Rectangle(new Point(0, 0), sizeF.ToSize());
            e.Graphics.DrawRectangle(new Pen(Color.Red, 1), layoutRectangle);            // Draw string to screen.
            RectangleF layoutString = new RectangleF(new PointF(0, 0), sizeF);//(0.0F, 0.0F, layoutArea.Width, layoutArea.Height);
            e.Graphics.DrawString(measureString, stringFont, Brushes.Black, layoutString, newStringFormat);