Abstract: To support selecting a proper way to theoretically calculate the navigation channel widths for large FPSO and the offshore oil platform’s towing operations, and also for helping them to make rules to guarantee the safety during towing process; to achieve this, this paper theoretically calculated the navigation channel widths for the 30 ton’s level FPSO ships first, in which the Approach Channel a Guide of Design of PIANC, the National Waterway Maneuvering Guidelines of Canada, the Rules of Harbor Designs of China, and also the homeland empirical ways of calculating the navigation widths of FPSO ships were referred, respectively; these calculated navigation channel widths were further validated via the navigation simulators’ experiments. Navigation simulator results suggest that, for those the FPSO ships at 30 ton’s level or above, both the navigation channel widths calculated by following the PIANC rules and the homeland empirical ways show high accordance with that of the real scenarios, and are therefore more acceptable and reliable. The results presented in this study are hence fruitful and meaningful for practices in towing operations of the large FPSO ships.