根据文档，段落间距是由边距定义的，这些边距不会累积(不加倍)，因此Julien Lebosquain的答案是正确的.

According to the documentation, Paragraph spacing is defined by margins, which do not accumulate (no doubling up), so Julien Lebosquain's answer is correct.

关于FlowDocument段落间距的MSDN