In this paper, a null means stationary series is reached which matched ARMA model after removing the long?term tendency, cyclical fluctuating and seasonal fluctuating one by one from Baltic Freight Index.

• 通过对波罗的海国际干散货运价指数分别提取长期趋势项、周期波动项和季节波动项以后；得到了一个符合ARMA模型建模要求的零均值平稳序列.