Abstract The aim of this study is to examine the potential seasonality of China's crude oil import in hope of helping the stakeholders with inventory control and production planning. In order to proximately achieve the goal, X-12-ARIMA method was used to adjust the monthly series and the quarterly series of China's crude oil net import in the last 16 years. The results show that the quarterly series is better than the monthly series in terms of seasonality adjustment; the seasonal factors tend to be positive in spring and summer quarters while negative in fall and winter quarters; and the former three seasonal factors are growing stronger while the winter factor weaker in recent years.