An optical imaging lens set includes: a first lens element with positive refractive power, a second lens element having an image-side surface with a concave portion in a vicinity of its periphery, a third lens element with positive refractive power, having a convex image-side surface, an object-side surface with a concave portion in a vicinity of its periphery, a fourth lens element having a concave object-side surface, and a plastic fifth lens element having an image-side surface with a concave portion in a vicinity of the optical axis. The total thickness Ta1 of the all lens elements along the optical axis, all four air gaps Gaa between each lens element along the optical axis, the thickness T3 of the third lens element along the optical axis and the thickness T5 of the fifth lens element along the optical axis satisfy the relation (Ta1+Gaa)/(T3+T5)≦4.00.