Taking　advantages　of　the　new　construction　and　complex　anchorage　techniques,　a　method　was　proposed,　with　takes　the　tension　force,　flexural　rigidity　and　length　of　hanger　rod　as　unknown　parameters　to　analyze　the　sensitivity　of　parameters　with　respect　to　natural　frequencies.　The　algorithm　based　on　sensitivity-updating　is　able　to　simultaneously　identify　the　tension　force,　flexural　rigidity　and　length　of　hanger　rod.　Then,　the　method　was　applied　to　four　different　hanger　rods　systems,　and　it　is　proved　that　the　proposed　method　is　of　high　accuracy,　and　can　be　applicable　to　the　rods　with　high　bending　stiffness.　A　testing　on　a　CFST　tied　arch　bridge　proves　the　field　applicability　of　the　method　presented.