first comment is that you should use strict; and use warnings; ..next, i think this shortens it up:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;
my $sur =     [
                     { 'one' => 'USA', 'two' => 'GOD', 'three' => '690
+557','four'=>'hello how are u',},
                     { 'one' => 'USA', 'two' => 'GOD', 'three' => '690
+557','four'=>'I am fine',},
                     { 'one' => 'UK', 'two' => 'GOD', 'three' => '6905
+58','four'=>'I am Okay',},
        ];
my %h;
foreach ( @$sur ){
  if( exists $h{ $_->{three} } ){
    $h{ $_->{three} } .= "####" . $_->{four};
  }else{
    $h{ $_->{three} } = join "<-->", @{$_}{ qw/one two four/ };
  }
}
print Dumper \%h;
[download]

I have to wonder though why @$sur is a hash with those keys instead of just an array ... can you explain where that data structure is coming from/what it's for?