The invention discloses automatic cable winding and unwinding equipment for an underwater robot, and an automatic winding and unwinding method. The equipment comprises a waterproof housing, a winding device, a control device, a power supply device, a communication device, and a power unit. The control device is in communication connection with the winding device, the communication device and the power unit. The winding device and the power supply device are disposed in the waterproof housing. The winding device is used for winding and unwinding a cable of the underwater robot. The control device is used for controlling the winding device to wind up or unwind the cable according to the received information transmitted by the underwater robot, and is also used for controlling the moving of the waterproof housing through the power unit. The power supply device is used for providing electric energy to the power unit, the winding device, the communication device and the underwater robot. The communication device carries out the communication with the underwater robot. The power unit is used for enabling the waterproof housing to move on the water surface and remain balance. The equipment and method provided by the invention improve the cable winding and unwinding efficiency for the underwater robot.