Everytime after load a cscope.out in Vim, I need to change Vim\'s \"pwd\" to the same directory as cscope.out file is under, which might be due to that cscope use relative path
@Aaron H. is right.
For my configuration I used the cscope_maps.vim plugin and modified the following lines:
40 " add any cscope database in current directory
41 if filereadable("/usr/project/cscope.out")
42 cs add /usr/project/cscope.out /usr/project
43 " else add the database pointed to by environment variable
44 elseif $CSCOPE_DB != ""
45 cs add $CSCOPE_DB
46 endif
Where "/usr/project" is the location of the cscope.out file and the absolute path I want to use.