An optical imaging lens system 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 first lens element has negative refractive power. The third lens element 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 fourth lens element has positive refractive power. The fifth lens element has negative refractive power. The sixth lens element has positive refractive power.