How can i measure total gnd current, the gnd is global net ?
Measuring current on a node is meaningless. You have to measure current through a branch, and so there needs to be a point at which you can probe the current. Often this would be through your supply source. Of course, if you have multiple supplies and want to measure the total ground return current, you'd have to sum up all the currents in each, or better still don't have a global ground, and insert an iprobe or zero-volt source in series with the ground pin before it connects to all the supply sources.
Thanks for the answer .
Actually i have large design of SRAM's , and i can't sum all current thru hierarchy, and i can't change the name of the net.
Do you know any way to get the current of the chip thru gnd! ?
Yes. As I mentioned, sum up the currents through the various supply sources connected to ground. I presume you don't have too many sources (or at least they're not scattered throughout the hierarchy), so presumably you could isolate those reasonably easily? You could always connect all your sources to a common node, and then connect that node to gnd! via an iprobe or zero-volt source - that way you've got just a single source to measure the current through, and don't have to sum up anything.