As the demand for clean energy sources like natural gas increases, the need for methods to measure the phase fraction of gas-liquid two-phase flows, which have complex and variable flow patterns, becomes more pronounced. This study introduces a phase fraction measurement method based on a cyclonic capacitive sensor. An effective cross-sectional phase fraction prediction model for the helical annular flow measurement section is established based on the capacitive signals. Using the drift flux principle, the dimensionless drift velocity of the helical annular flow is analyzed, and a volume gas fraction (GVF) prediction model based on the "inverse drift flux method" is established. Experimental results show that this method is suitable for a wide range of phase fraction measurements and is highly accurate. When the liquid volume fraction (LVF) is less than 10%, the average relative error of the predicted GVF is 0.3%; for the LVF from 10% to 30%, the average relative error is 1.4%.