Abstract: The need to employ a high-speed fluid jet scouring technique is a key to performing the dredging operations underwater. It is of crucial value to effectively improve the efficiency of jet mud-making for river (waterway) dredging and reservoir capacity restoration projects. This article adopts the methods of sediment starting and transportation experiment and flow field numerical simulation using a high-speed jet scouring process to study the influence on the riverbed under several hydraulic factors. The distribution characteristics and attenuation law of jet velocity are thoroughly analyzed, and an effective mechanism of sediment scouring via high-speed jet has been developed. The results indicate that there is an optimal flushing distance during the jet mud-making process that enhances its highest growth rate as well as water turbidity. It has been observed that the time-average velocity distribution and the attenuation of the maximum velocity at the centerline section of the jet cross-section are similar. The growth rate of the jet half-width in the initial development zone remains the same for studied jet velocities. The efficiency of the jet scouring process is directly related to the resistance loss during the jet development and subsequent energy loss upon reaching the bed surface. Therefore, determining an optimal height for jet nozzle arrangement is critical for enhancing the mud-making efficiency. The presented results could potentially transform the existing dredging equipment with an enhanced jet mud-making capacity as well as its speed.