The invention relates to an easily-tested misplug-proof locking electric connector, which comprises a plug and a socket, wherein the plug comprises a rectangular plug shell; the plug shell is providedwith a contact mounting cavity; the inside of the contact mounting cavity is provided with a plug contact element; the plug is provided with a test through hole positioned on the side wall of the plug shell and relative to the position of the plug contact element; the test through hole is provided with an inner port communicated with the contact mounting cavity and an outer port positioned on theouter surface of the side wall of the plug shell; and a connecting component for preventing the misplug and locking is arranged between the plug and the socket. In the connector of the proposal, theside wall of the plug shell and a plug insulator are provided with a through hole and a test hole which are mutually communicated, and one end of the test hole extends to the position of the plug contact element. Therefore, a probe of a test device can directly pass through the through hole and the test hole to reach the position of the plug contact element and is electrically connected with the plug contact element, so the test device can conveniently test or measure current or a signal flowing through the connector.