Due to the advantages of small volume and simple structure

the cladding mode of the in-fiber interference sensor is used widely. Therefore

the investigation of the sensing mechanism and improvement of the measurement performance are the key factors to study this sensor. By using the finite difference beam propagation method

the interference spectrum of the sensors with removing partial of cladding and bending are simulated in this paper. The order of dominant cladding mode is obtained by comparing dispersion equation and spatial frequency spectrum after Fourier transform. The results show that

compared with normal sensor

the orders and numbers of cladding modes both increase. Meanwhile

with the increasing of bending radius within limits

the cladding modes order increase.