A hydraulic brake signal transmitter comprises a pipe, a piston, a penetrating part and signal pins; the pipe comprises an inlet, an outlet and a side opening, wherein the side opening is connected with the inlet and the outlet; the inlet and the outlet of the pipe are used for connecting a brake oil pipe; two ends of the penetrating part are provided with one reception abutting surface and a conducting surface; the conducting surface of the penetrating part faces the two signal pins; the piston is installed inside the side opening; the piston is provided with an oil push surface and an abutting surface which are arranged back to back; the oil push surface is used for pushing with oil; the abutting surface pushes and abuts the reception abutting surface of the penetrating part; the conducting surface of the penetrating part is in touch with and is electrically connected with the two signal pins.