In order to improve the quality of the Bessel beam generated by a deformable mirror and explore the factors that influence its quality, the influences of the ring number of the deformable mirror actuator and the incident angle of the beam on the beam quality are studied. When generating a conical phase with 10-μm amplitude, the root mean square value of the residual error decreases from 70 nm to 26 nm while the ring number increases from 3 to 5. The distribution of axial light intensity of the generated Bessel beam is closer to the ideal distribution. This result indicates that the increasing ring number of the deformable mirror actuator can effectively improve Bessel beam quality. In addition, Bessel beams are generated by beams with incident angles of 15°, 30°, and 45°. The experimental results show that the Bessel beam quality is good and unaffected by the incident angle. This paper provides recommendations and references for generating high-quality Bessel beams by using deformable mirrors, and these recommendations are expected to be beneficial for the applications of Bessel beams.