A mid-infrared cavity is implemented herein on a valley photonic crystal structure with a honeycomb lattice via manipulation of the valley degrees of freedom. The resulting topological waveguide designed considering this structure exhibits remarkable unidirectional transmission characteristics, achieving near-unity forward transmission efficiency within the operating frequency range while effectively suppressing backward scattering. The cavity constructed on the basis of this design achieves a quality factor of 5.59×10⁴ within the target frequency range. When compared to conventional photonic crystal cavities, this mid-infrared cavity exhibits a significantly lower inverse participation ratio that reaches as low as 1.6 and consistently remains below 2 within the target frequency range. This results in significant mode field distribution uniformity. Moreover, the mode distribution of the cavity remains stable even when structural defects are introduced.