The present disclosure discloses an optical imaging system including sequentially, from an object side to an image side along an optical axis, a first lens, a second lens, and at least one subsequent lens. The first lens may have: a first transmission surface disposed on an outer circumference of an object-side surface of the first lens; a first reflection surface disposed on an outer circumference of an image-side surface of the first lens; a second reflection surface disposed at a paraxial region of the object-side surface of the first lens; and a second transmission surface disposed at a paraxial region of the image-side surface of the first lens. A distance TTL from a center of the object-side surface of the first lens to an image plane of the optical imaging system on the optical axis and an effective focal length f of the optical imaging system may satisfy: TTL/f≤0.6.