I have a excel graph (line graph) and a number of series data, One series is much larger then the rest thus makes the rest of the data series look straight lined,
I need to put a axis break in the y-axis so a certain range on y-axis is hidden

any ideas anyone

Check out this site:

http://andypope.info/charts/brokencolumn.htm

Andy is one of the best for Excel charts.

thanks gone into website and its a bit more difficult for line graph for me anyway, but looks achievable..thanks

Have you tried this:

Right click on the straight-lined series, select 'Format Data Series', then 'Axis' tab page and 'Secondary Axis'

Maybe this will help you.