Due to the virtue of directly measure mass flow, the Coriolis mass flowmeter is the first choice of international trade settlement in recent years. It has become one of the most rapidly developing flowmeters. Although the accuracy of Coriolis mass flowmeter is relatively high, it has the weakness of zero-point drift, which could result in long-term instability. Based on the characteristics of amplitude-frequency and phase-frequency of the classic U tube in the sensor, this article analyzes the responses of each order to the working vibration frequency. The model of the initial phase of the sensor is formulated. By prototypes testing, this zero-point model is suitable for thin-walled pipe structure and can be widely used. It reduces the error of Coriolis mass flowmeter in cryogenic flow measurement to be within ±0. 3% , and also provides a theoretical foundation to reduce the zero-point drift of Coriolis mass flowmeter.