Bridge deflection response is on e of the most important indicators used for structural condition assessment of bridges.There are currently many methods and devices for deflection measurement,but they are not satisfying in terms of economy,applicability,and measurement accuracy at the same time.This paper proposed a rapid and highly accurate method for measuring mid-span deflection of small and medium-span bridges.By using the high accuracy of displacement transducers in direct contact measurement,an auxiliary measurement device was developed to transfer the deflection of the measurement points on the bridge to the displacement transducer in the form of a rigid connection,thus achieving accurate and dynamic testing.A coupled vehicle-bridge-derrick system model was developed,and model tests were carried out simultaneously to compare the displacement deviation between the measurement points on the bridge and the monitoring point under vehicle loading and verify the feasibility of the proposed method for dynamic response testing.The effect of transverse wind load on the transfer accuracy of the device was simulated and calculated.The results show that the measurement deviation caused by the transverse wind load is less than 5% for the 12 m-long transfer rod,proving that the proposed test method has high accuracy and practicality.