The utility model relates to a 10kV current transformer on-line detection device which comprises a host and an extension set which are connected through a wireless communication module. The host comprises a host pincerlike mutual inductor, a host A/D converter, a host wireless communication module and a host single-chip microcomputer. The extension set comprises an extension set pincerlike mutualinductor, an extension set A/D converter, an extension set wireless communication module and an extension set single-chip microcomputer. The main machine pincerlike mutual inductor is connected with asecondary wire of the secondary wiring meter box current transformer, the auxiliary machine pincerlike mutual inductor is connected with a high-voltage wire, contact between a main machine and high voltage is avoided, and the auxiliary machine is safe and reliable to operate by adopting a high-voltage insulating rod.