Abstract: Sand production of horizontal well restricts the normal production of oil and gas fields seriously and even results in oil well failure and other accidents. At present, the sand washing based on tool swirling jet is the conventional sand washing technology, but its washing effect on fixed sand bed is not quite satisfying. In this regard, the in-tool pulsed jet sand washing technology was proposed and the internal pulsed jet tool was developed. Then, the numerical model for the pulsed jet sand washing of horizontal section was established based on Eulerian two-phase flow model. Finally, the sand washing effect of pulsed jet was compared with that of swirling jet, and the sensitivity parameters were analyzed, e.g. jet frequency, sand washing displacement, sand bed height and sand particle diameter. It is indicated that compared with the swirling jet, the sand washing efficiency of internal pulsed jet is much higher and the time consumption is 37.5% shorter. And the sand washing efficiency is optimal when the pulse frequency is 0.71 Hz, the sand bed height is less than 12.5 mm and the sand particle diameter is shorter than 0.8 mm. It is expected that experimental study can be carried out on the internal pulsed jet sand washing tool in the following step. The calculation results of numerical simulation can provide the guidance for the preparation of experimental scheme.