A headlamp unit based on a polarizing beam splitter, comprising a lens and at least a polarizing beam splitter, wherein viewed from a reverse light path, parallel light is refracted twice by an incident surface and an emergent surface of the lens and then converged in at least two focuses through the polarizing beam splitter, each of the at least two focuses (A and B, or, A, B and C) corresponds to a light path system, and the light path systems may be turned on simultaneously or separately to obtain a corresponding headlamp light pattern; characterized in that either, the polarizing beam splitter enables the lens to have two focuses, imaging of two independent optical systems is achieved respectively, the two optical systems are two lower beam systems, the two optical systems synthesize a light shape through the polarizing beam splitter, and after passing through the lens, the light shape irradiates a road surface to form a complete illumination light shape; or, an arrangement of multiple polarizing beam splitters enables the lens to have a plurality of focuses, imaging of a plurality of independent optical systems is achieved respectively, the plurality of optical systems are a plurality of upper beam systems and a plurality of lower beam systems, -the plurality of optical systems synthesize a compound light shape through the arrangement of multiple polarizing beam splitters, and after passing through the lens, the compound light shape irradiates a road surface to form a complete illumination light shape; and in that: the two or plurality of lower beam optical systems are subjected to beam combination through the polarizing beam splitter, a common lower beam illumination function is achieved when light sources of the two or plurality of lower beam optical systems are all turned on, and a W-grade light shape in an AFS rule is achieved when one or more of the light sources are turned off or the brightness of one or more of the light sources is reduced. comprising a lens and at least a polarizing beam splitter, wherein viewed from a reverse light path, parallel light is refracted twice by an incident surface and an emergent surface of the lens and then converged in at least two focuses through the polarizing beam splitter, each of the at least two focuses (A and B, or, A, B and C) corresponds to a light path system, and the light path systems may be turned on simultaneously or separately to obtain a corresponding headlamp light pattern; characterized in that either, the polarizing beam splitter enables the lens to have two focuses, imaging of two independent optical systems is achieved respectively, the two optical systems are two lower beam systems, the two optical systems synthesize a light shape through the polarizing beam splitter, and after passing through the lens, the light shape irradiates a road surface to form a complete illumination light shape; or, an arrangement of multiple polarizing beam splitters enables the lens to have a plurality of focuses, imaging of a plurality of independent optical systems is achieved respectively, the plurality of optical systems are a plurality of upper beam systems and a plurality of lower beam systems, -the plurality of optical systems synthesize a compound light shape through the arrangement of multiple polarizing beam splitters, and after passing through the lens, the compound light shape irradiates a road surface to form a complete illumination light shape; and in that: the two or plurality of lower beam optical systems are subjected to beam combination through the polarizing beam splitter, a common lower beam illumination function is achieved when light sources of the two or plurality of lower beam optical systems are all turned on, and a W-grade light shape in an AFS rule is achieved when one or more of the light sources are turned off or the brightness of one or more of the light sources is reduced.