Compared with ordinary Ushape and Δshape Coriolis mass flowmeters, the microbend type Coriolis mass flowmeter has lager measurement error in measuring gasliquid (airwater) twophase flow because it has a higher natural frequency and smaller phase difference. To reveal the characteristic of gasliquid twophase measurement error, the flow sequence is obtained by adapting a zerocrossing detection method based on experimental data of the microbend type Coriolis mass flowmeter. The distribution pattern of the flow sequence is analyzed with the probability density. The mathematical model of the flow sequence is built by the correlation analysis and its veracity is confirmed. The mathematical model consists of a stable component and a fluctuating component. The stable component corresponds to the mean value of the practical flow measurement and the difference between it and the true value of the flow measurement reflects the gasliquid twophase flow measurement error of the microbend type Coriolis mass flowmeter. The fluctuating component reflects the stability of the instantaneous flow measurement.