好的，关于我之前的评论，我现在找到了解决方案.

Okay, regarding my previous comment, I now found a solution.

似乎 toFile 绕过了 $skipXMLDeclaration 而 toString 没有.所以以下工作:

It seems toFile bypasses $skipXMLDeclaration whereas toString doesn't. So the following works:

$XML::LibXML::skipXMLDeclaration = 1;

my $doc  = XML::LibXML::Document->new;
# create your document

print $doc->toString;

(非常小的)缺点是您必须自己编写文件.

The (very small) downside is that you have to write the file yourself.