Abstract: In this paper,the flow field simulation of the gas trapping phenomenon in the propellant pipe caused by the liquid sloshing,rotating or liquid level collapse is carried out.The study found that the lower the height of the anti-collapse disk is,the less liquid is left in the tank,the greater the flow resistance is,the larger the diameter of the disk is,the later the collapse occurs,and the disk diameter has a smaller effect on flow resistance.When there are vortex and sloshing,the liquid level collapse will occur earlier,but the vortex elimination and anti-collapse device can still effectively delay the occurrence of gas trapping in the propellant pipe.The research can provide reference for the design of vortex elimination and anti-collapse device.