An insulator is disclosed, which includes an insulating surface. A part of the insulating surface is applied with a conductive coating having a specific resistivity. A conductive coating region having the specific resistivity and a nonconductive coating region are configured that: in a dry environment, no continuous conductive channel exists between upper and lower fittings of the insulator. The value of the leakage current that can be caused by the conductive coating region having the specific resistivity on the insulating surface enables the insulating surface to reach an ice-proof temperature in an icing climate condition. Also, a power transmission apparatus in which the insulator is adopted is disclosed. In an icing climate condition, the conductive coating can achieve the function of increasing the value of the leakage current on the surface of the insulator, so as to prevent the ice formation.