Graphene oxide（GO） film as humidity sensitive layer is fabricated on the surface of the microcantilever by copper ring auxiliary coating method.The displacement deflection change of the sensor under different relative humidity（RH） are studied.The water-absorbing expansion and water-loss shrinkage of the GO film cause the deflection of the microcantilever to change.The optical lever detection principle is used to amplify the displacement deflection of the free end of the microcantilever to obtain the relationship between the displacement deflection of the sensor and the humidity.The results show that linear correlation between humidity change and displacement deflection is 0.993 6 in relative humidity measurement range of 18 %～77 %RH

and the sensor sensitivity is about 82.93 nm/%RH.Four consecutive cycle tests show that the trend of the sensor is the same and displays good measurement repeatability in relative humidity measurement range of 20 %～ 77 %RH.Deflection trend of sensor is basically the same.The response time of sensor is 5 s and the recovery time is 10 s.The sensor has the advantages of fast response and good repeatability.It has potential application prospects in miniature humidity sensors.