Abstract: With the exploitation of oilfield and increase of auxiliary exploitation methods, the sand content of produced liquid becomes increasingly high. Although mechanical desanding and chemical sand control are adopted in the borehole, there is still a great deal of fine sand deposited in the surface gathering system vessel. Generally desanding of large tank adopts manual desanding that requires personnel to enter the tank after shutdown, with high work burden, severe environment, long shutdown time and low efficiency. This paper introduces a new method that is based on the principle of free, submergence jet stream, there is a pipe network set with sand washing orifice is set at the bottom of the tank, the power source of desanding is fire water near the tank, the automatization of desanding that does not requires entering the tank is realized.