The utility model discloses a special main insulation state detecting device of a capacitive current transformer. The device comprises a current collection fixing end which is mounted on a tail screen grounded wire of the capacitive current transformer and is used for detecting current data, a voltage transformer secondary end which is mounted on a same bus and a same phase of a detected current transformer, a voltage collection fixing end used for detecting grounded voltage, and a handheld data collection moving end, wherein the current collection fixing end, the voltage transformer secondary end and the voltage collection fixing end are connected with one another by virtue of a 2.4GHz wireless communication network. Detection specialists detect the capacitance of the capacitive current transformer in a transformer substation site by virtue of detection manner and detection device and complete the detection work of the insulation state of the capacitive current transformer.