The present disclosure relates to a vehicle lighting system, and discloses a headlight optical element. The headlight optical element includes a light incident portion, a transmission portion and a light emergent portion. The light incident portion includes at least one light incident structure; the transmission portion is arranged between the light incident portion and the light emergent portion, and includes a light transmitting portion located at the center, and light absorbing portions located on the periphery; and the light emergent portion includes a light emergent surface protruding outwards. The headlight optical element has the advantages of simple structure and convenient dimming. The present disclosure further discloses a headlight module adopting the headlight optical element, a vehicle headlight including the headlight module, and a vehicle adopting the vehicle headlight.