Effects of transient waves' dynamic forcing on the northward jump of jet and the westward movement of jet center from early summer to midsummer are studied by using NCEP/NCAR daily reanalysis data.The result shows that the transient waves' dynamic forcing is favorable to the northward jump of the jet,but not favorable to the westward movement of the jet center.Then the relationship between the occurrence time of East Asian Subtropical Westerly Jet variations from early summer to midsummer and anomalies of transient waves is further studied.The analysis revealed that the dynamic forcing of the transient anomalies has a positive feedback effect on the occurrence time of the jet's northward jump and a negative feedback effect on the occurrence time of the jet center's westward movement.So the transient waves' dynamic forcing has important influence on the variations and occurrence time of the East Asian Subtropical Westerly Jet from early summer to midsummer but exerts significantly different effects on the Jet's northward jump and its center's westward movement.