Vehicle light optical element, vehicle light module, vehicle headlight and vehicle

An vehicle light optical element (1) related to the technical field of vehicle lighting. The optical vehicle light element (1) comprises a light incident portion (10), a light transmission portion (11), and a light emitting portion. Two ends on the light transmission portion (11) in a light emitting direction are respectively a light incident end and a light emitting end. The light incident portion (10) comprises at least one light incident structure (13) provided at the light incident end of the light transmission portion (11) and corresponding to a light source (20). The light emitting portion comprises a light emitting surface (12) protruding from the light emitting end of the light transmission portion (11) towards the light emitting direction. A cross-sectional area of the light transmission portion (11) gradually increases from the light incident end to the light emitting end. The light incident portion (10) and the light emitting portion of the vehicle light optical element (1) are provided on the same optical structure. Therefore, no optical path needs to be built, and an assembly relationship is simple, thereby simplifying the structure of the vehicle light optical element (1), and improving optical system precision of the vehicle light optical element (1).