Abstract: The trawl winch is an important equipment for trawlers.Data for theortical ana-lysis for its pull load have not been published as yet.In this paper, various fact-ors affecting pull load of trawl winch are being analysed completely. Derived calcu-lation method of pull load for various steps of hauling the trawl net was based onstatic balance and D'Alembert's principle in calm water and rough-sed. Finally, re-sult of actual ship experiment had been re-calculated by this method. The result ofthis paper was confirmed and may be designed for practical use and for productionof trawl winch.