Animated transitions help viewers understand changes between related visualizations. To clearly present the underlying relations between statistical charts, animation authors need to have a high level of expertise and a considerable amount of time to describe the relations with reasonable animation stages. We present AniVis, an automated approach for generating animated transitions to demonstrate the changes between two statistical charts. AniVis models each statistical chart on the basis of a tree-based structure.Given an input chart pair, the differences of data and visual properties of the chart pair are formalized as atomic transition units.Through this approach, the animated transition between two charts is expressed as a series of transition units. Then, we conduct a preliminary study to understand people's preferences for animation sequences. Based on the study, we propose a set of principles and a sequence composition algorithm to compose the transition units into a meaningful animation sequence. Finally, we synthesize these units together to deliver a smooth and intuitive animated transition between charts. To evaluate our workflow, we implement a web-based system and demonstrate its generated results to illustrate the usage of our approach. We perform a comparative study with the latest method to assess the animated transitions automatically generated by our system. We further collect feedback from experts to evaluate the usability of our method.CCS Concepts: • Human-centered computing → Visualization systems and tools;