Terahertz　imaging　technology　has　been　widely　used　in　various　fields.　In　continuous-wave　terahertz　imaging　system,　when　the　large　size　object　is　located　at　the　unfocused　position,　Bessel　beam　with　non-diffractive　properties　show　its　large　depth　of　focus　advantage　over　Gaussian　beam.　Bessel　beam　can　be　generated　by　the　axicon,　which　has　high　conversion　efficiency.　The　non-diffraction　distance　and　the　main　lobe　size　of　the　Bessel　beam　depend　on　the　parameters　of　the　axicon　and　incident　light　wavelength.　We　analyzed　that　the　influence　on　the　axial　two-dimensional　intensity　distribution　of　a　zero-order　Bessel　beam　by　changing　the　axicon　parameters　and　the　incident　Gaussian　beam　size.　Experimentally,　the　axicon　with　different　parameters　were　fabricated　using　different　materials.　Then　the　two-dimensional　intensity　distribution　of　the　Bessel　beam　in　the　axial　and　transverse　direction　were　recorded　and　analyzed.　The　experimental　results　is　basically　consistent　with　the　theoretical　ones.