The invention relates to a rocket normal-temperature liquid propellant filling device and a method for eliminating filling liquid flow entrained gas. The filling device comprises a filling tank and agas releasing tank. The filling tank is provided with a first control valve and a second control valve. The first control valve is used for being connected with an extrusion gas source through a gas compressing pipeline. The second control valve is connected with the bottom of the gas releasing tank through a filling pipeline. The filling pipeline is provided with a third control valve. The top ofthe gas releasing tank is provided with a filling connector used for connecting a rocket engine fuel storage tank, and the rocket normal-temperature liquid propellant filling device has the beneficial effects of being simple in structure, convenient to use, safe and reliable; entrained gas in rocket normal-temperature liquid propellant filling liquid flow can be effectively eliminated, and the work stability of a rocket engine is guaranteed. The method for eliminating filling liquid flow entrained gas has the beneficial effects that the technology is simple, implementation is easy, and the entrained gas eliminating effect is good.