n.someone devoted to the promotion of human welfare and to social reforms
同义词：humanitarianimprover
英汉双解大词典
do-gooder(do-gooders)
1.
N-COUNT（可数名词）
If you describe someone as a do-gooder, you mean that they do things which they think will help other people, although you think that they are interfering. 不实际的社会改良家[表不满]