Abstract: An adjustment process in erosion and accretion was discussed on the riverbed sediment in the Jiaojiang mountain-seream macrotidal estuary with the data of the observed tidal current,suspended sediment and anthropogenic activity,based on the GIS digitized and calculated sediment erosion and accretion on the riverbed using 19 bathyorographies in different years in the recent 70 a.It was shown that the adjust ment between erosion and accretion on the riverbed underwent the more remarkable four stages either on the transverse and longitudinal profiles or on the riverbed planes in this estuary,the average erosion-accretion rate on the riverbed planes,however,was more approachable to ward the whole area than that on the transverse and longit udinal profiles % (1) it was in slowly scoured state and the erosion region made up 65.4% in the study area where the average annual scouring rate was 2.3 cm/a or 537 000 m³ by the dominant natural action between 1933 and 1962;(2) it was transformed from the slow erosion into the clearer accretion and its region taken up 66.2% in the entire area where the average annual depositing rate was 2.2 cm/a or 504000 m³ by the influence that the reservoir was built up on the upper reaches of the tributary Yongning River between 1962 and 1984;(3) it was changed from the accretion into the slight erosion and its region accounted for 62.6% on the whole area where the average annual scouring rate was 1.8cm/a or 414 000 m³ by the action that the partial work construction was completed for the navigable channel regulation between 1984 and 1990;(4) it was developed to wards the direction of the accelerating erosion from the slight one and its region occupied 71.5% in the study area where the average annual scouring rate was 5.6 cm/a or 1 308 000 m³ between 1990 and 2003.This implies to a certain extent that the adjustment between erosion and accretion on the riverbed sediment is subjected to human impact stronger than nature in the Jiaojiang Estuary.