A lamp head assembly includes an outer head unit, an inner head unit, and an elastic pressing unit. The outer head unit includes at least two conductive pins. The inner head unit is disposed rotatably in the outer head unit. The elastic pressing unit is disposed movably in the outer head unit for selectively positioning the position of the inner head unit relative to the outer head unit or the position of the outer head unit relative to the inner head unit, wherein the elastic pressing unit includes a pressing element selectively exposed from the outer head unit.