Data journalism，based on big data and visual representation，is constantly broadening the boundaries of news reporting，but there are also some difficulties in its development. The “unclean” data source，the error of data analysis，the bias of the algorithm and the inappropriate visual presentation will affect its authenticity and objectivity. At the same time，from the perspective of news ethics，data journalism will violate citizens’ right of informed consent and personal privacy to a degree. Therefore，this paper discusses the development and ethical dilemma faced in the process of data journalism，and attempts to make corresponding suggestions from the aspects of strengthening data review，increasing data disclosure，establishing professional supervision platform and improving relevant management regulations.