In this study, we employ optical spatial filtering to improve the quality of the Bessel beam generated by a deformable mirror. An annular filter is designed to filter the spectral components produced by the round tip error of the deformable mirror on the spatial spectrum plane of the generated Bessel beam, making the axial intensity distribution of the Bessel beam increasingly uniform. Furthermore, a filter that combines a sectorial filter and an annular filter is designed, which directly transforms a circularly symmetric Bessel beam into an elliptic Bessel beam. The aspect ratio of the main lobe of the generated elliptical Bessel beam is approximately 1.72. The axial full width at half maximum exhibits a maximum of 247 mm, denoting an excellent non-diffraction property. The proposed optical spatial filtering method can effectively improve the performance of the Bessel beam generated by a deformable mirror and advance its applications.