The utility model discloses a contact line protection system of continuous beam for over-passing an electric railway. The contact line protection system is characterized in that a protection scaffolding is arranged above the existing railway, and is formed as follows: top scaffolding longitudinal beams are supported by scaffolding uprights on both sides; steel shims and square timbers are laid on the scaffolding longitudinal beams to form a cast-in-situ portal; a continuous beam bottom die for constructing the continuous beam is laid on the square timbers; and a high-voltage electric insulation plate wraps the surfaces of the I-beams of the scaffolding longitudinal beams at the middle stage of the scaffolding longitudinal beams so as to form electric insulation of the scaffolding longitudinal beams to the high-tension wires of a contact line. According to the contact line protection system provided by the utility model, the height occupied by the structure can be reduced effectively by combining the protection scaffolding with the cast-in-situ portal, and good protection function and good cast-in-situ support function are achieved.