The present invention relates to the field of rainproof devices for transformers, in particular to an embedded rainproof cover for an oil flow speed relay. The embedded rainproof cover comprises a cover body; the cover body is of a horn mouth shaped structure that the top end is closed and a caliber is gradually increased from the top end to the bottom end; an accommodation chamber for accommodating the oil flow speed relay is defined by an inner cavity of the cover body; a notch groove is axially and concavely formed at the bottom end of the cover body, and a connecting buckle for connecting two notches is arranged at the positions of the notches of the notch groove; and the connecting buckle, and the groove wall and the groove bottom of the notch groove define a passing passage for a connecting oil pipe for connecting the oil flow speed relay with a main transformer to pass through. According to the embedded rainproof cover disclosed by the present invention, while disassembling rapidness and convenience of a current relay rainproof device can be promoted, requirements on in-batch and low-cost production can also be ensured; and the rainproof cover is very high in cost performance, and can effectively meet the increasingly efficient, rapid and convenient modern electricity installation requirements.