Abstract: The members of a long span suspension bridge model are often very small due to scaled size reduction. The large sensors are thus not allowed to be installed on the model in consideration that the additional mass, stiffness and damping will affect the test results, especially in dynamic tests. In this experimental investigation, the naked optical fiber Bragg grating sensors were used to measure the strain of hanger ropes of 0.5 mm diameter and other small members. In order to obtain the transfer function of strain to an exciting force, a fiber optic impact hammer was developed. The strain mode shapes of the bridge model were measured. The results obtained from the tests can be used as references for structural health monitoring of the prototype bridge. Furthermore, some experiences obtained from the tests are presented in this paper.