Confocal Brillouin microscopy (CBM) provides a non-contact, non-destructive, and high spatial resolution measurement, which has widely been applied in biomedical detection, physical chemistry, and materials science. The Brillouin scattering frequency is low, and the intensity is weak, so the signals can be easily overlapped or even overwhelmed in the case where the elastically scattered light is not sufficiently suppressed, which significantly limits measure accuracy of the Brillouin spectrum. In addition, the spectral axial resolution and tomography ability of CBM is still insufficient, which limit applications in the fields of high scattering samples and large working distance. In this paper, a D-shaped divided aperture confocal Brillouin microscopy (DDACBM) is proposed to improve the anti-elastic scattering ability, spectral axial resolution, and tomographic capability of CBM. DDACBM eliminates the backscattering light and reduces the crosstalk between the elastic scattering and Brillouin scattering by symmetrical lateral offset illumination and lateral offset detection.Thus the anti-elastic scattering ability of CBM is improved. And the point spread function of the illumination light path and the collection light path is modulated. The illumination light path and the collection light path only overlap on the focal plane by the inclined incident. Therefore, threedimensional point spread function is compressed in the z-axis, and the interference between the defocused plane and the focal plane is effectively removed. The full width at half maximum and a full maximum of the axial spectral intensity response curve reduce, thereby the spectral axial resolution and tomography ability of the CBM are improved. Experiments show that DDACBM improves the anti-elastic scattering ability and tomographic capability of the CBM. And by optimizing the pupil parameter, the spectral axial resolution is improved by more than 30%, which can effectively reduce the spectral crosstalk in multi-layer samples. DDACBM provides a guarantee for further applications of Brillouin spectrum technology in the modern basic research fields.