【Background】The oriental fruit fly （Bactrocera dorsalis Hendel） has been gradually spreading northwards in recent years due to the change of plantation structure and transportation of infested fruit from south to north. It became a great threaten to fruit industry in north. 【Method】Population dynamics of the oriental fruit fly in citrus orchard at Linhai, Zhejiang Province, was systematically monitored by sex pheromone traps during 2008~2010. Combining with meteorological data and field surveys, models were built, using the numbers of adults and meteorological data at 10-days intervals. 【Result】The oriental fruit fly at Linhai had a single-peak population curve. Adults started to appear in late June to early August and the population peaked between early September and early November. After this, the population decreased until late December when adults were not captured any more. The model analysis showed that the 10-days average temperature determined the annual peak, while rainfall was an important factor in seasonal population dynamics through influencing soil moisture. Both higher temperatures and higher soil moisture were positive factors. 【Conclusion and significance】The study will contribute to improving forecast and allowing for a more effective control of this invasive species.