The concave corner structure has excellent vibration and noise reduction characteristics to effectively attenuate the structural vibration response, honeycomb structure with excellent mechanical properties has been more commonly used in engineering, so the composite structure of concave corner honeycomb has attracted the attention of scholars. A novel phononic crystal model was created using the inner concave honeycomb structure' s fractal design. Based on the finite element method, the fractal concave angle honeycomb structure was analyzed to calculate the energy band structure and vibration transmission characteristics, as well as to examine the negative Poisson ratio characteristics of the structure and the effect of the structural fractal on the vibration band gap. By varying parameters such as wall thickness and the angle of the inner concavity, filling the steel at the apex of the fractal structure can provide better suppression of certain frequency bands of vibration. The results show that the fractal structure still has negative Poisson ratio characteristics, the fractal structure produces a wider band gap in the second-order structure, the increase in wall thickness and concave angle causes the structural vibration band gap to shift to the high-frequency region, the filled steel causes the band gap to widen. [ABSTRACT FROM AUTHOR]