Theoretical analysis and experimental research was done on relation between the light source coherence degree and the maximum diffraction-free distance of the generated Bessel beam. A collimated partially coherent beam generated by a rotating ground glass illuminated by a He-Ne Laser was impinged on an axicon to generate partially coherent Bessel beam. Moving the position of a rotating ground glass to change the coherent degree of the light source, and measure the maximum diffraction-free distance of the generated Bessel beam with different coherence degree, the relation between the light source coherent degree and the maximum diffraction-free distance of the generated Bessel beam were obtained. A Gaussian shell model source was used in theoretical analysis and numerical simulation, the results show that the maximum diffraction-free distance suffers a rapid decline when the coherence degree decreased a little. If the coherence degree of the source decreased from g≈1 to g=0.8, the maximum diffraction-free distance will be only a half of the original, the experimental results is coincident with the theoretical analysis.