Hi Kim,
You also need to set the chart bounds mode to Stretch:
chart.BoundsMode = Nevron.GraphicsCore.BoundsMode.Stretch;
as by default the chart will try to preserve the specified aspect ratio. 
Let us know if you meet any problems or have any questions.

Best Regards,
Nevron Support Team

Hello Team,

I want to set chart size like below :

NChart chart = nChartControl1.Charts[0];
chart.Size = new NSizeL(new NLength(20, NRelativeUnit.ParentPercentage), new NLength(80, NRelativeUnit.ParentPercentage));

But, The width and length shrinks at the same time.(even though I really want my chart to be vertically long)
How can I make my chart be sized respectively for width and height ?