A lens assembly includes a lens holder and a lens barrel that are coaxial and integrated in a unity, a cavity is defined therein to receive at least one lens, at least three guiding legs are extended from a bottom of the lens holder, and the guiding legs define a plane that is parallel to an installation plane of the lens. It can achieve an accurate optical axis alignment between the lens and the image sensor, reduce total assembly tolerances of the camera module thereby improving imaging quality, and reduce manufacturing cost to benefit the popularization in industries.