Abstract: In order to analyze the characteristic of displacement amplification ratio of flexible bridge-type micro-displacement amplifier,a quarter mathematic model is established by using the symmetrical structure of bridge-type micro-displacement amplifier.The formulas for calculating output displacement and displacement amplification ratio of the bridgetype amplifier are derived by adopting the matrix method to deduce the compliance matrix of the mechanism.Finite element simulation is carried out by software ANSYS11.0,and then compared with the theoretical model.Finally,an experimental sample is designed and fabricated to verify the theoretical model.The results show that the displacement amplification ratio of the amplifier is most sensitive to the distance between two flexure hinges;as the distance increases,the displacement amplification ratio increases sharply at first and then decreases slowly;theoretically speaking,the amplifier can get a displacement amplification ratio for more than 40 times,but the error will be amplified at the same time,so the displacement amplification ratio of the bridge-type micro-displacement mechanism should not be too large.