Abstract: The life cycle of Aurelia coerulea consists of two stages: the benthic polyp stage and the planktonic medusa stage; however, the polyp stage is often neglected because of the difficulty in detecting and identifying these tiny individuals. In this study, we chose three key environmental factors, i.e. temperature, salinity and illumination, to clarify their effects on the settlement and metamorphosis of A. coerulea planula in laboratory. The results revealed that 21 ℃ was the optimal temperature for the settlement and metamorphosis of A. coerulea planula, and the duration of settlement at 12 ℃ was the shortest (48 h). In the salinity test (18~33), the settlement rate of A. coerulea planula increased with the salinity decreasing. In the illumination test (0~300 Lux), the settlement rate of A. coerulea planula increased with the illumination enhancing. This study may contribute to monitoring and management of moon jellyfish blooms in coastal waters of China.