The invention relates to the technical field of devices for detecting wool yarns of thermoplastic glass fibers, in particular to a device and method for detecting wool yarns of thermoplastic glass fibers. The device comprises a plastic rod which is connected with the output end of a motor by virtue of a motor and is wound by broken wool yarns, wherein a current sensor for detecting current of the motor is arranged on the motor and is in communication connection with a PLC controller; the output end of the PLC controller is respectively connected with an alarm and a contactor which is used for controlling starting and stopping of the motor; the output end of the contactor is connected with the motor. The device for detecting wool yarns of thermoplastic glass fibers is capable of detecting the wool yarns winding around a roller in time.