One face of a substrate of a diffuser with a light condensing function is disposed with a plurality of prism rods; at least one inclined face of parts of prism rods is disposed with a rough diffusion face; the diffusion face may be positioned on any position of the inclined face of the prism rod; the diffusion face is disposed with a plurality of irregularly arranged raised and indented stripes perpendicular, not perpendicular or parallel to a crest line of the prism rod; chromatid dispersion can be reduced and stripes of the prism rods can be atomized effectively by utilizing the diffusion face to eliminate the occurrence of moiré fringes and elevate the yield factor.