Abstract: To meet the technical requirements of fiber optical guidance (FOG), the influence laws of such structural parameters as fiber optical wave guide coredelta, core diameter, dentclad and inner coating on the bend loss of bend insensitive optical fiber are discussed. A bend insensitive optical fiber is manufactured by plasma chemistry vapour deposition(PCVD) process with authors' patent, and the relevant parameters are tested. The test result shows that the bend loss of the new optical fibermeets the requirement for FOG. Through the discussion about the optical cable design scheme, the feasibility o f this optica l fiber/cable application to underwater vehicles is forecasted.