In this paper,a free-space vortex generator based on Bessel beam dif fraction is designed.The Bessel beam propagates in a single-mode fiber (SMF) through a spiral phase disk at the end of the fiber, and then evolves into a vortex beam,which is modulated in free space.The finit e-difference time domain (FDTD) software is used to analyze the generator's operating wavelength range, polarization sensitivity and processing tolerance.Comparing the results of the vortex beam with differen t topological values propagating in the free space for 100μm,the proposed fiber vortex generator h as the non-diffractive properties of the Bessel beam naturally obtained in the fiber,which can produce a specific Bessel beam.The beam has potential applications in high-resolution imaging,particle capture an d manipulation.