The lens assembly may include a housing, a first group lens assembly disposed in the housing, and a second group lens assembly disposed at one side of the first group lens assembly. The first group lens assembly may be a fixed lens assembly, and may include a first lens and a liquid lens. The second group lens assembly may be a movable lens assembly and may include a second lens group. The first group lens assembly may have a negative () refractive power as a whole, and the second group lens assembly may have a positive (+) refractive power as a whole.

The disclosure relates to an optical system and a camera module. The optical system sequentially includes a first element group and a second element group from an object side to an image side along an optical axis, wherein the first element group sequentially includes, from the object side to the image side: a first lens having a positive refractive power, a reflective element, and a second lens having a negative refractive power, and the reflective element is configured for reflecting light emitted from the first lens; the second element group has a positive refractive power, and the second element group is able to move in a direction along the optical axis, so that the optical system switches between a short-focus state and a long-focus state; and the optical system satisfies 0.39<DL/DEFL<0.49.