Abstract: A lead-in clamp with electric wire protective casing are disclosed. The electric wire protective casing is a long plastic roll tube, whose longitudinal free edges are not sealed, but rather can be expanded out and drawn back, on the roll tube there being formed a series of uniformly spaced transverse recesses. The lead-in clamp comprises left and right clamp stems, left and right clamp bodies and a clamping spring. When the left and right clamp bodies are fitted together, a wire passing cylinder and a casing guiding head are formed. When in use, the wires are put into the wire passing cylinder, then insert the casing guiding head into one end of the wire protective casing tube. After the wire protective casing tube is fixed stationary by hand, the lead-in clamp is pushed toward the other end of the wire protective casing, thereby to encase all of the wires into the wire protection casing.