This study explored the differences in the effects of directive versus reflective feedback on elementary school students' conceptual understanding and epistemological beliefs in a simulation-based online science inquiry environment, by comparing more fine-grained differences in the inquiry behaviors of students who received the two types of feedback during the online scientific inquiry activity. Seventy-one 5th graders from a public elementary school in China participated in the study (38 students receiving directive feedback and 33 receiving reflective feedback). The results showed no significant difference between the two types of feedback on the students' conceptual understanding and epistemological beliefs. However, reflective feedback outperformed directive feedback on the subdimension of source of epistemological beliefs, and directive feedback outperformed reflective feedback on the argumentation subdimension. In addition, the average inquiry time of the students receiving reflective feedback during the review session was significantly longer than that of the students receiving directive feedback. These results provide important insights for elementary teachers to implement feedback in science classrooms.