Much research has focused on the prediction field; however, few are concerned about the detail between forecasting and influence factors. It is an important area to help decision-makers decide in time. River and relevant factors were studied utilizing variance decomposition and cross-spectral analysis. The results show that there is an inflection point between the shipping volume and the related variables. After passing a high-speed development period, the inland shipping volume will enter a stable period of fluctuation, and the correlation with other variables will gradually decrease. The amplitude spectrum verifies the degree of influence; the cross-spectral analyzed each variable is driving relationship; the phase spectrum shows the shipping volume and the time required for effecting.