The method involves detecting a cable tension measuring value in real-time by performing digital filter process. A cable tension actual value is obtained. A time cable tension error and a tension error change rate are obtained by performing difference operation on the cable tension actual value and a cable tension preset value. A fuzzy controller is designed by considering the cable tension error and the tension error change rate as an input signal. An electric control proportion of a towing winch direction valve control signal is considered as an output signal.