<p>The vortex flowmeter is a highly accurate and versatile speed-type flow monitoring instrument widely used in the aerospace industry. In single-phase fluid flow within pipelines, vortex flowmeters demonstrate high accuracy and meet industrial production requirements. However, bubbles are always inevitably mixed in to form a gas–liquid two-phase flow, which can adversely affect the measurement accuracy of the flowmeters. To address this, numerical simulations were conducted to study two-phase gas–liquid vortex flow meters in horizontal pipelines at low temperatures. The influence law of the gas content in the two-phase flow on the measurement accuracy of the vortex flowmeter and the mathematical relationship between the gas volume fraction and the instrument coefficient <i>k</i> were analyzed. The results indicate that a law similar to the variation of the vortex street is also generated for the gas after it flows through the bluff body. With an increase in gas content, the generation of vortices is affected by bubbles, thereby influencing the shedding frequency of vortices and reducing their energy. Finally, by employing the fitted linear relationship between the flowmeter coefficient and the gas volume fraction, the measurement error of the flowmeter was reduced from 6.5 to 0.74%. This reduction is significant for guiding practical engineering applications.</p>