In order to solve the problem of simultaneous multi-parameter measurement with a fiber optic sensor, we proposed a novel biconical optical fiber grating structure based on combination of the tapered optical fiber and optical fiber grating. The reflection spectral characteristics of the biconical optical fiber grating were analyzed by using the transfer matrix method, the fundamental mode effective refractive index dispersion equation of two- and three-layer single-mode fiber and the scalar finite element method. The reflection spectrum was illustrated when the diameter of uniform erosion region was 3 μm. The hydrofluoric acid etching was used to prepare the biconical fiber Bragg grating. When the diameter of uniform erosion region was 3 μm, 12 reflection peaks including 2 primary peaks and 10 secondary peaks were observed, which is consistent with the theoretical analyses. Furthermore, three of the resonance peaks were selected to test the sensing response to temperature, refractive index and liquid level. The simultaneous detection sensitivity was found to be 9.63 nm/℃, 1975.96 nm/RIU and 26.07 nm/cm, respectively. This biconical fiber grating has a simple fabrication process, it can be used as the multiple-parameter sensors with low cost, and it can also extend the design concept of optical fiber sensor.