Abstract: Micro cantilevers in atomic force microscopy are important force sensors in nano research,and the young’s modulus is one of the most important parameters of the cantilevers.Normal testing methods are not suitable for the young’s modulus detecting of micro cantilevers according to the strict scale of the cantilevers,and new methods are needed to the study of micro cantilevers.A new method for detecting of young’s modulus of micro cantilevers based on combining the numerical simulation and frequency measurements is presented in this paper.The new method involves two steps,the first step is developing the vibration model of the micro cantilever studied immersed in air and analysis the vibration behaviour of the corresponding cantilevers with the same geometry but different young’s modulus.The second step is measuring the natural frequency of the micro cantilever studied experimentally and compare the experimental results with the numerical results to determine the young’s modulus of the cantilever.Experiments on a NSC cantilever have been done to validate the method presented in this paper.