Since the introduction of flipped learning, it has drawn much attention and enjoyed increasing popularity. This study attempts to investigate Chinese English majors' metacognitive strategy use in a flipped environment and the influencing factors of metacognitive strategy use. 35 subjects were asked to study the assigned online course video lectures out of class and participate in activities demanding the application of acquired knowledge. Students' metacognitive strategy use and factors influencing their use were analyzed based on the data collected from written reflections, interviews and classroom observations. Findings indicate that 1) planning, self-monitoring, self-evaluation, directed attention and selective attention are students' main employed metacognitive strategies in and out of the flipped classroom, 2) factors influencing students' metacognitive strategy use consist of students' desired learning outcomes and group learning, and students' self-control over learning pace in the flipped context further motivates their use of diverse metacognitive strategies.