Calliope is a novel visual data story generation platform that employs advanced AI techniques to automatically analyze data and represent data insights in the form of narrative visualization. It helps non-expert users create visual data stories from an input spreadsheet through an automatic process without any technique barrier. It also facilities the easy revision of the generated story based on an online story editor. To better support easy sharing and communication, Calliope further incorporates a public website with social features such as story exploration, sharing, rating and comments. The evaluation shows the usability and usefulness of the platform.