The slow light propagation in a line defect waveguide in chalcogenide photonic crystal of As2S3 rods in air medium has been investigated.It is found that the filling factor of the chalcogenide photonic crystal and the size of defect rods decide the propagation of the guided mode.An increase in the filling factor results in a sharp decrease of the group velocity in the photonic crystal waveguide.It has been demonstrated that,by tuning the filling factor and size of defect rods,the group velocity will be reduced up to about 0.22c. The slow light propagation in a line defect waveguide in chalcogenide photonic crystal of As2S3 rods in air medium has been investigated. It is found that the filling factor of the chalcogenide photonic crystal and the size of defect rods decide the propagation of the guided mode. An increase in the filling factor results in a sharp decrease of the group velocity in the photonic crystal waveguide. It has been been demonstrated that, by tuning the filling factor and size of defect rods, the group velocity will be reduced up to about 0.22c.