Abstract: Aimed at the technical difficulty of significant measurement error in large-flow-rate liquid natural gas （LNG） Coriolis mass flowmeters, with LNG as the research object and focusing on the large-caliber straight-tube type （DN400） Coriolis mass flowmeter, a low-temperature fluid-solid coupling numerical model was established.Simulation studies on the two modes （dry mode and wet mode） of the Coriolis mass flowmeter were conducted to explore the influences of the arrangement shape of the measurement tube, the structural parameters of the measurement tube, and the low-temperature physical properties of LNG on the modes of the Coriolis mass flowmeter.The research results indicate that the single straight-tube type measurement tube has a higher natural frequency and a smaller amplitude, which increases the difficulty of extracting signals from the detection equipment.The six straight-tube type has a lower natural frequency and is more susceptible to interference.For the double straight-tube type and the four straight-tube type, their natural frequencies are moderate, overcoming the deficiencies of the former.Meanwhile, it is found that the shorter the measurement tube length and the thicker the wall thickness, the higher the natural frequency.By analyzing and comparing the calculation results of the dry and wet modes, it is discovered that under the influence of the fluid added mass effect on the modal characteristics of the measurement tube, the natural frequency of the wet mode is significantly lower than that of the dry mode.However, due to the low density effect and low-temperature effect of LNG, the corresponding reduction in the natural frequency is less than that when water is the working medium.At this point, the measurement accuracy of the flowmeter can be enhanced by adjusting the shape of the measurement tube and the pipeline arrangement, actively altering the natural frequency and phase information of the measurement tube to obtain an appropriate excitation frequency, reduce environmental interference, and thereby achieve efficient resonance.In the resonant state,the measurement tube can generate a larger amplitude,facilitating signal collection and processing.This research provides certain technical support for the structural design and accuracy improvement of large-flow-rate LNG Coriolis mass flowmeters.