But the width of my report is 11.125 means A4 size. How its possible to cut my half page? Report's orientation is Landscape but its margin in layout view seems like portrait. You can see in the image below:
You have reached the ultimate problem with any report in any language - excessive data density. You need to either set the DESCRIPTION field with .CANGROW = 1 and shrink its .WIDTH or you need to use a REALLY small font or you must accept that you will truncate something. You have too much data to be displayed in that format.