Enactment of scientific inquiry in classroom has attracted a great attention of science educators around the world. In this study, we examined two competent teachers' (one Grade 9 chemistry teacher and one Grade 4 science teacher) enactment of scientific inquiry in selected teaching units to reveal the characteristics of enacted inquiry at different grade levels by analyzing lesson sequence videos. The coding schemes for enacted inquiry consist of ontological properties and instructional practices. Pre-topic and post-topic teacher interviews and the two teachers' responses to a questionnaire were adopted to identify the factors influencing teacher's enactment. The results indicate that the two case teachers' enactment involved a range of inquiry activities. The enacted inquiry at fourth-grade level covered all the inquiry elements, tending to engage students in the whole procedure of inquiry. The ninth-grade chemistry class placed emphasis on the elements "making plans" to solve problems in authentic context. Important factors influencing the enactment include teacher's understanding about scientific inquiry, textbooks, assessment, students and resource. Implications for inquiry enactment and instruction improvement have been provided.