This article presents a method for real-time 3-D imaging and velocity measurement of two-phase flows using a twin-plane electrical capacitance tomography (ECT) sensor with 24 electrodes. A dedicated digital ECT system with a data acquisition rate of 241 frames/s is used for capacitance measurement. In this article, the sensitivity distribution of the ECT sensor is analyzed, and the two most commonly used algorithms, linear back projection (LBP) and Tikhonov, are used to achieve high-speed 3-D image reconstruction. The cross correlation technique is used to calculate the velocity of a two-phase flow. Experiments were carried out to evaluate the performance of the proposed method. Several typical distributions were constructed and used to analyze the axial imaging resolution. A free-falling sphere was used to test the ability of the system in velocity measurement. Experimental results show that the proposed method can provide high axial resolution in the central zone of the 3-D sensor and high temporal resolution in velocity measurement.