Capacitively coupled contactless conductivity detection (C4D) is a new detection technique has been developed in recent years and used mainly in capillary electrophoresis and microchip electrophoresis. The characteristics of C4D detector are simple in structure, easy in miniaturization and integration, and free of electrodes contamination, which are common problems in an electrochemical detection. The principles and progresses of C4D in capillary electrophoresis are reviewed.