A synchronous double-rotary-drum mooring rope paying off winch comprises two rotary drums and a driving device. The two rotary drums are arranged on a rotary drum shaft through bearings in a penetrated mode respectively, two ends of the rotary drum shaft are respectively installed on two parallel lateral plates, and a large gear is fixedly connected with the outside of a rim at one end of each rotary drum. A middle shaft is installed between the two rotary drums and parallel to the two rotary drums and penetrates through the two lateral plates through bearings. A driving small gear is installed at one end of the middle shaft on the inner sides of the lateral plates and meshed with the large gears installed on the two rotary drums simultaneously. The driving small gear is driven by the driving device. A motor of the driving device is arranged on the outside of one lateral plate and fixed on a base. A brake is respectively connected with an output shaft of the motor and an input shaft of a gear speed reducing device. An output shaft of the gear speed reducing device is connected with the middle shaft. The winch can achieve synchronous same-direction rotating of the two rotary drums. The motor shaft can be braked immediately to brake the winch when emergent braking is required. Traction force of the winch is improved.