Trond, I am pretty sure this is a viewport issue. The OP is working through a viewport that was left unlocked...someone clicked inside it and zoomed/panned around, and now it's not scaled as it was meant to be.
If you're in paperspace, and select the 'zoom to extents' and 'center the plot' features, they only affect the page setup in paperspace. In other words, they have no affect on the objects that exist in modelspace. That view is controlled entirely through the viewport.
Without knowing more about the relationship between model space and paper space in this drawing (specifically, the intended scale factor), it's hard to suggest a good way to get them lined back up properly. There is an Express Tool designed to rectify this exact problem, if Express Tools are installed on that machine. It's called ALIGNSPACE. But if Express Tools aren't already in your ACADE install, you'd have to add them in via Add/Remove programs.
shuo.huang, if you're familiar with the differences between modelspace and paperspace, I might be able to walk you through a solution. If we can't get you together that way, you can always post the drawing here on the forums, or you can send it to my personal email if there are concerns about confidentiality. I'll attempt to fix the file for you if you do.
Here's a suggestion that *might* work, but it depends on a couple things:
**first thing, is there anything in model space that is outside of the tiny rectangle that we see in the image you posted? If not, continue. If there is, this idea won't work.
**second thing, verify the viewport is UNLOCKED: right click on it, and in the resulting shortcut menu, go to Display Locked>No.
*Now,while you're in paperspace, double-click the mouse wheel to perform a ZOOM EXTENTS. (Alternatively, enter Z on the command line, followed by E.) Then, double-left-click inside the viewport to move your crosshairs into model space. You will still be looking at paper space, but can now affect objects in model space. You'll see that if you move your cursor to the edge of the viewport, it shifts from being the ACAD crosshair, to being just a normal mouse pointer. If you double-click at this point, you will return to paper space and the crosshairs will replace the mouse pointer.
*Next, double-click in the viewport to go back into modelspace. Perform another ZOOM EXTENTS. Note: DO NOT ZOOM OR PAN AFTER YOU DO THIS. What this should do, is expand modelspace to fit inside the viewport that you are currently inside of.
*next, before doing anything else, double-left-click outside the viewport and return to paperspace. Right-click on the viewport, and set it to be Display Locked>Yes.
*Do one last ZOOM EXTENTS. At this point, you should be seeing everything that exists in model space taking up your whole viewport.
Try this, and post back with your results. If it doesn't work, or if my explanation wasn't clear enough, see if you can post the file and I'll take a look at it to see what's up.

Jim Seefeldt
Electrical Engineering Technician