The invention relates to a marine seismic prospecting towing line power supply length prediction method. The marine seismic prospecting towing line power supply length prediction method comprises steps that (1)a marine seismic prospecting towing line power supply system model is established; (2) equations are established according to the step (1); (3) the related parameters of the marine seismic prospecting towing line power supply system is set; (4) the equations are solved, and the marine seismic prospecting towing line power supply length and the power consumption of the marine seismic prospecting towing line power supply system are calculated. The marine seismic prospecting towing line power supply length prediction method is advantageous in that prediction precision is improved, and use is simple and convenient, and the marine seismic prospecting towing line power supply length is effectively predicted.