The invention provides a draining device of a cleaning tank. The device comprises an operation switch, a drain plug mechanism, and a connection steel wire. The operation switch is provided with an up-down moving part and a button. One end of the connection steel wire is connected with the up-down moving part. The operation switch is provided with two retention positions, such that the up-down moving part can stop at different heights, and the connection steel wire can be withdrawn and released. The drain plug mechanism comprises a water cap and an elevation connection rod thereof. The other end of the connection steel wire is connected with a transmission mechanism which drives the elevation connection rod to elevate. The invention also provides a cleaning tank with the draining device. According to the invention, the opening and closing of the draining device can be realized through the operation switch, and the state of open or close can be stably maintained at the positions thereof. The operation of the device provided by the invention is more convenient, and satisfies human application habit. Water storage/draining can be realized by a slight push by using a finger or an elbow. The device is environment-friendly, convenient, and easy-to-use. The device has good sealing effect and long service life.