The utility model belongs to the technical field of the automobile manufacturing technique and specifically relates to a dimming system and vehicle headlamps is related to, dimming system includes lens support assembly, the nut of adjusting luminance, adjust luminance executor assembly and locating part, the half opening mounting groove of motor bulb matched with of adjusting luminance and being provided with on the nut and adjusting luminance the executor assembly, the motor bulb is connected with half opening mounting groove, and the nut of adjusting luminance is connected with lens supportassembly again, and the locating part setting is on lens support assembly to can keep off the opening part of establishing at half opening mounting groove. In this scheme, the opening part of double opening mounting groove of locating part carries out the shutoff after the installation finishes to realize that the motor bulb is blocked up in the nut of adjusting luminance, the nut of adjusting luminance can not break away from with the motor bulb, has avoided the inefficacy of motor dimming function, and this kind of new structure can improve the lamps and lanterns security performance, reduces the car potential safety hazard.