The utility model provides an air -core type reactor's rain -proof cap structure, includes two at least split type rain -proof caps, makes up into a rain -proof cap main part, rain -proof cap main part is concatenation or overlap joint one -tenth integral type, and its surface is provided with the strengthening rib, and the wiring round has been offered on the surface. Rain -proof cap is arc or half dome, and its top is provided with the semicircle ring, the arm of being qualified for the next round of competitions on rain -proof cap lower extreme is less than, rain -proof cap surface covering has the polyester material layer. Rain -proof cap main part is the calathiform. The utility model discloses under assurance self intensity, expose the strengthening rib in rain -proof cap surface, can reduce rain -proof cap thickness, weight reduction. The wiring round has been offered to rain -proof cap, reduces the mounting height of rain -proof cap when being convenient for the wiring, and the last arm of being qualified for the next round of competitions of messenger lies in the rain -proof snow effect of the inside reinforcing of rain -proof cap. It is convenient for hoist to set up the hole for hoist in the backup pad.