A new method based on electrical capacitance tomography (ECT) in conjunction with the ant system was proposed to measure the void fraction of oil-gas two-phase flow.The 12-electrode capacitance sensor of ECT system could obtain 66 measured capacitance values.The void fraction measurement model parameters f and b

which were obtained by the least square method in advance

were determined according to the flow pattern that was first identified by the ECT system.Then the most important combined capacitance set which had decisive influence on the void fraction of a given state of measurement was obtained based on the ant system

and the corresponding pheromone of the ant system was regarded as the weight of this set.The capacitance set and its weight were simultaneously input to the measurement model to obtain the void fraction.The experimental results showed that the proposed method for the void fraction measurement was effective under different flow patterns owing to avoidance of complex image reconstruction and good real-time performance.The maximum error was less than 5.5% as compared with the quick closing valve method

and the measurement time was within 0.08 s.