An ECT data acquisition system usually has N-1 measurement channels or single measurement channel. In order to solve the contradiction between system speed and system cost, a 16-electrode electrical capacitance tomography system with double measurement channels has been designed. It has good anti-noise ability and stray-immunity by using ac-based capacitance measuring circuits. A switch network is used to set each electrode at excitation mode, detection mode or idle mode. The influence of switch coupling capacitances is discussed and its soft compensation method is proposed. By using LabVIEW, remote monitoring and distributing data or images over network can be implemented easily.