During the treatment of natural orifice disease using flexible interventional instruments, such as catheter and gastroscope, there are two problems: the uncertain response between proximal operation and distal motion and tissue damage owing to release of the deformation energy. This paper employs flexible operation of instruments to decrease surgery risk by introducing in-vivo perception and local close-loop position control. Three-dimension interaction force between instruments and tissue was sovled inversely via distance measurement by fiber reflecting based on force-position transformation realized by elastomer. Steerable freedom of instruments is combined with force to realize local close-loop control. Then ablation catheter was used as an application case to evaluate the effectiveness of the control strategy. Simulation results and preliminary experiments indicated that the flexible operation method could decrease the contact force rapidly and protect human tissues effectively.