An optical imaging lens assembly, sequentially arranged from an object side to an image side along an optical axis, comprising: the first lens element with positive refractive power having a convex object-side surface, the second lens element with negative refractive power having a convex object-side surface and a concave image-side surface, the third lens element with positive refractive power having a convex image-side surface, the fourth lens element with refractive power having both optical surfaces being aspheric, the fifth lens element with refractive power having a concave image-side surface and both optical surfaces being aspheric, wherein a stop and an image sensor disposed on an image plane are also provided. By such arrangements, the image pickup optical system satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with camera functionalities.