Using transfer matrix method and finite element method, the influences of fabrication and structure factors, such as grating period, modulation depth, diameter of waist and length ratio in different regions, on the spectral characteristics of the biconical fiber Bragg grating were analyzed. The simulation results demonstrate that when other grating factors remain unchanged, the reflection spectrum of the biconical fiber Bragg grating red-shifts with the increasing of grating period. This change trend is in accord with that of the uniform fiber Bragg grating. However, when the modulation depth is enhanced, the two main peaks does not shift, but the number of secondary peaks between the two main peaks increases and intensity is enhanced. Moreover, with the decrease of the cone waist diameter, more cladding modes are excited, and more interference peaks with enhanced intensity are observed. When the grating length is kept at 1 cm, the length ratios between waist region, standard grating region and gradient grating region will impact the number and the amplitude of the secondary peaks directly. With the increase of the gradient grating region length, the number of secondary peak decreases but the amplitude increases. In a word, by properly designing the grating factors, the biconical fiber Bragg grating can be widely used in multi-parameter sensors, multi-channel filters, multi-channel semiconductor laser, dispersion compensation and OADM.