The invention relates to a cleaning device for cleaning a conveying belt and a glass substrate conveying system including the cleaning device. The cleaning device comprises a brush mechanism for cleaning the conveying belt and a telescopic mechanism. The telescopic mechanism is connected to the brush mechanism through an elastic mechanism. The cleaning device comprises a cleaning position and a non-cleaning position. At the cleaning position, the telescopic mechanism stretches out, the brush mechanism elastically abuts against the conveying belt, and at the non-cleaning position, the telescopic mechanism draws back, and the brush mechanism is spaced from the conveying belt. According to the cleaning device, the conveying belt can be cleaned efficiently and stably, a conveyor does not need to be shut down in the cleaning process, normal production tasks are not influenced, and the capacity of equipment is improved. In the glass substrate conveying process, the cleaning device is used for cleaning away glass dust on the conveying belt, the influence of the glass dust on the quality of glass substrate products is avoided, and therefore the product quality of a glass substrate is improved.