Non-diffracting beams possess advantages of better direction and far distance for applications to free-space communications. During free propagation, their profiles of transverse intensity remain nearly invariant in a range. Some non-diffracting beams have orbital angular momentum. By analyzing the characteristic of the beam with orbital angular momentum and non-diffracting beams transmission, the computer-generated hologram was used as spatial light modulator with reflective phase modulation to implement optical transformation. Laguerre-Gaussian beam carrying the information is transformed to a higher-order Bessel non-diffractive beam with the same topological charge by a mode converter consistina of axicon. A method of encoding and decoding of optical communication was proposed based on the non-diffracting high-order Bessel beams with orbital angular momentum. The proposed approach not only ensures the security of atmospheric laser communication, but also improves the density and precision of information transmission greatly.