_latest("dire1");
...do something...
_latest("dire2");
...do something...
_latest("dire3");
...do something...
_latest("dire4");
...do something...

sub _latest{

 my $file  = shift;
 
 my @dir;
 my $saved_time = -1;
 my $saved_name = '';
 
 sub wanted {
 if(-f $File::Find::name)
 {
      if ((stat($File::Find::name))[9] > $saved_time) 
     {
            $saved_time = (stat($File::Find::name))[9];
            $saved_name = $File::Find::name;
        }
 }
 }

 @dir = ($file);
 find(\&wanted, @dir);
 return $saved_name;

}
[download]

I don't know how to reset the variable to (-1, '') in this mode. In my opinion,every time I call _latest function,it reset the variable. But test result is not like that. It don't reset. Would you please help me ? thanks!

Did you turn on warnings? Don't you get a "Variable ... will not stay shared" warning for you code? If you do, read perldiag about that message. Your error is still that your variables are not reset, except in a more complicated manner.