Simulated transmission spectra for tapered fibers with no taper, one taper and two tapers in the near infrared wavelength range, calculated by Finite-Difference-Time-Domain method are currently presented. Transmission peak positions tend to shift to the shorter wavelength when the taper deformation is added to the fiber or the taper width gets narrower. The thickness sensitivity for the tapered structures with different taper thicknesses is about 2.28e-3 nm·μm−1. There is an interference structure in the electric field distribution images, which reveals in the fiber structures. The transmission spectra for the fiber without taper, one taper and two-tapered structures were simulated in near infrared wavelength by FDTD. The transmission spectra for tlated in near infrared wavelength by FDTD. The sensitivity of the fiber was about 50 nm × RIU−1 and it had better refractive index detection. The tapered fiber can be applied to the bio-chemical sensors and physical deformation testing.