The embodiment of the invention discloses a tread defect detection method and system. The tread defect detection method comprises the following steps of: photographing a laser image of a tread by utilizing a three-dimensional camera; and judging whether a connector and a central line of the tread have defects or not by a controller according to laser height information in the laser image. The laser image photographed by the three-dimensional camera is provided for the controller; in a rotating process of a belt ply drum, the laser height information in the laser image is analyzed by the controller, and whether the connector and the central line of the tread have the defects or not according to the laser height information; if the connector or the central line has the defects, an alarming device is controlled to output an alarming signal; and then the tread is adjusted by a worker. If the connector and the central line have no defects, a signal is transmitted to a molding drum by a transferring ring and the next step of operation is carried out. By adopting the tread defect detection method disclosed by the invention, whether the tread has the defects or not does not need to be manually detected, so that the defect detection speed is increased, and furthermore, the production efficiency of tires is improved.