An optical image assembly includes six lens elements, which are, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The second lens element with negative refractive power has an object-side surface being concave in a paraxial region thereof and an image-side surface being convex in a paraxial region thereof. The third lens element has positive refractive power. The fourth lens element has positive refractive power. The fifth lens element has positive refractive power. The sixth lens element has negative refractive power.