The periodical cutting location of Jingjiang beach in recent years and the cutting scale of the sand body and the scale of the downward-moving central bar are analyzed，and the time and discharge of 12 large-scale cuttings that occurred since 1966 are studied. The result shows that cutting may occur both in flood season and dry season，the cutting discharge during low tide in the flood season is between 38 700～54 100m3/s （47 000 m3/s average），and the cutting discharge during high tide in the dry season is between 11 800～23 700 m3/s （17 000 m3/s average）. We may strengthen the terrain observation when reaching the cutting discharge，predict the channel crossing time，and allocate the dredging equipment in advance to reduce the impact of siltation on channel operation，which is of great significance to the maintenance and dredging of the channel.