HI 

I try to install office 2013 KB2986156 to all my laptop (Win8.1) in school via SCCM2012R2.

But I found the icon is different from other update, it is grey. and I try to download it, it show the following error"

"All software updates in this selection are expired or meta-data only, and cannot be downloaded"

Add 'expired' and 'superseded' to the console's view and you'll find out why the icon is grey. 

See:

Technical Reference for the Icons Used for Software Updates

That update is expired -- you can't do anything with it. It was superseded by 3054938 which in turn has been superseded by 3055