The invention belongs to the technical field of optical cable preparing and discloses an optical fiber tension adjusting device. The optical fiber tension adjusting device comprises a rack. A detecting mechanism used for winding an optical fiber and detecting the tensioning force of the optical fiber, a collecting and releasing mechanism used for being matched with the detecting mechanism to achieve collecting or releasing of the optical fiber, and a control system which is used for receiving information fed back by the detecting mechanism and adjusting the collecting and releasing speed of the collecting and releasing mechanism according to the fed back information so as make the optical fiber have certain tensioning force are arranged on the rack. The detecting mechanism and the collecting and releasing mechanism are sequentially arranged on the rack. The rack is provided with the detecting mechanism so that the tensioning force of the optical fiber can be detected through the detecting mechanism; the collecting and releasing mechanism is arranged on the rack so that the collecting and releasing mechanism can be matched with the above detecting mechanism to achieve collecting andreleasing of the optical fiber; and the control system is arranged so that the collecting and releasing speed of the collecting and releasing mechanism can be adjusted according to the information fed back by the detecting mechanism, and therefore certain tension of the optical fiber can be kept all the time in the moving process of the optical fiber.