The brake pad wear sensor is a device designed to remind vehicle owners to replace brake pads in a timely manner. Its working principle is as follows: when the brake pad wears down to the limit, the wear sensor will be naturally worn through. At this time, a signal is transmitted to the ECU (Electronic Control Unit), triggering the brake warning light to turn on and alerting the driver to replace the brake pads promptly. The brake pad wear sensor consists of a steel plate, an adhesive heat insulation layer and a friction block. The heat insulation layer is made of non-thermal conductive materials to prevent heat transfer. The friction block is composed of friction materials and adhesives; it comes into contact with the brake disc or brake drum to generate friction during braking, thereby achieving vehicle deceleration and braking.