I am using Auto cad 2008 & the plotter is HP Design jet 610.  While plotting in A1  the full paper width is not printing.  That means 841 mm is coming on length wice.  Only 594 mm is using as width .I am using a paper roll of width 841mm. Please help me

You should change the orientation of your plot settings from vertical to horizontal or viceversa, depending on how the page is now configured. You can find this in the lower right corner of the plot window when you are about to plot the drawing.
It may be a good idea using preview before plotting to avoid surprises like you've got.