I had run the two versions of regedit on command line. I found the 32bit regedit.exe didn't contain "Wow6432Node" at all, the 64 bit version provide that node. As my program export always "Wow6432Node" node into the .reg file, I don't think what I called is a 32 bit version.

I dont understand what you want to do. You have a .reg file, that needs to be applied, without redirection, to the registry? Then use the 64bit regedit. If your .reg file is getting the redirection, then you are calling the 32 bit regedit. You have to use an absolute path with "Sysnative" folder (google it) in it to reach the 64 bit regedit from a 32 bit perl.

I can't find "windows/sysnative" folder on both my win7 and win2k3(64bit). I only see "sysWOW64" in Winodws folder.

goto C:\WINDOWS\SysWOW64 in explorer, double click on cmd.exe,

Microsoft Windows [Version 5.2.3790]
(C) Copyright 1985-2003 Microsoft Corp.

C:\WINDOWS\SysWOW64>cd ..

C:\WINDOWS>cd Sysnative

C:\WINDOWS\Sysnative>
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Only 32 bit processes can see it. It doesn't exist in a 64 bit process. Server 2003 x64 used for above example (I did apply the MS patch to enable sysnative on server 2003 btw). If I try a normal (64 bit) cmd.exe I get

C:\WINDOWS>cd Sysnative
The system cannot find the path specified.

C:\WINDOWS>
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I use the following sub to grovel through registry looking for installers which may be of interest to you:

sub FindXXXSoftware {
    my ($resetNoModify) = @_;

    return if !$^O eq 'MSWin32';

    my @result;

    eval {
        require 'Win32/API.pm';
        require 'Win32/TieRegistry.pm';
        require 'Win32API/Registry.pm';

        my $pathPrefix = 'LMachine\SOFTWARE';
        my $wowPath    = 'Wow6432Node';
        my $pathSuffix = 'Microsoft\Windows\CurrentVersion\Uninstall';
        my $root =
            Win32::TieRegistry->new($pathPrefix,
            {Access => Win32API::Registry::KEY_READ()});

        my @products;

        for my $subPath ($pathSuffix, "$wowPath\\$pathSuffix") {
            my $uninstall = $root->Open($subPath);

            next if !$uninstall;
            $uninstall->Flush();

            my @entries = $uninstall->SubKeyNames();

            for my $entry (@entries) {
                my $entryKey = $uninstall->Open($entry);
                my $name     = $entryKey->GetValue('DisplayName');
                my $pub      = $entryKey->GetValue('Publisher');
                my $noModify = $entryKey->GetValue('NoModify');

                next
                    if !defined $name
                        || !defined $pub
                        || $pub !~ /^XXX/i;

                eval {
                    delete $entryKey->{NoModify};
                    return 1;
                }
                    or warn
                    "Registry DeleteValue failed for 'NoModify' agains
+t $name\n"
                    if defined $noModify && $resetNoModify;

                push @result, {entryCode => $entry, name => $name};
            }
        }

        return 1;
    };

    return @result;
}
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Thanks for your code.

It took me some time to understand. But sorry maybe I didn't catch the point, for I didn't see how you resolve the problem of 32bit program accessing a 64bit program's registry in 64bit OS

In fact, any trying of accessing to "HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\" will be redirected to "HKEY_LOCAL_MACHINE\\SOFTWARE\\Wow6432Node\\" automatically. That means I can never get content of "HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\" branch, which is what I want using a 32bit Perl program and different from "HKEY_LOCAL_MACHINE\\SOFTWARE\\Wow6432Node\\"

The Perl code I wrote is like what you have written somewhat, but didn't work as I wished. I spent a lot of time to check why I didn't get the correct content as seeing from regedit. Later I understand by searching websites that the WoW64 is doing the redirecting...

I had a similar problem and solved it like:

use Win32API::Registry qw(:ALL);

...

if( RegOpenKeyEx( HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Cryptograp
+hy", 0, KEY_READ|0x0100, $key ) ) {
  RegQueryValueEx($key, "MachineGuid", [], $type, $nodeId, []);
  RegCloseKey( $key );
}
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The point is 'KEY_READ|0x0100'. From http://msdn.microsoft.com/en-us/library/aa384129%28VS.85%29.aspx:

#define KEY_WOW64_64KEY 0x0100
    Access a 64-bit key from either a 32-bit or 64-bit application.
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regards