An optical imaging system comprising ten lens elements, the ten lens elements being, in order from an object side to an image side along an optical path, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element, an eighth lens element, a ninth lens element and a tenth lens element, a total number of lens elements of the optical imaging system is ten, and each of the ten lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side; wherein the optical imaging system further comprises an aperture stop, the first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof, the image-side surface of the first lens element is concave in a paraxial region thereof, the second lens element has negative refractive power, the object-side surface of the second lens element is convex in a paraxial region thereof, the image-side surface of the second lens element is concave in a paraxial region thereof, the object-side surface of the third lens element is convex in a paraxial region thereof, the mage-side surface of the third lens element is concave in a paraxial region thereof, the object-side surface of the eighth lens element is convex in a paraxial region thereof, the image-side surface of the eighth lens element is concave in a paraxial region thereof, the ninth lens element has positive refractive power, the object-side surface of the ninth lens element is convex in a paraxial region thereof, the image-side surface of the ninth lens element is concave in a paraxial region thereof, the tenth lens element has negative refractive power, the image-side surface of the tenth lens element is concave in a paraxial region thereof, and at least one of the object-side surface and the image-side surface of the tenth lens element has at least one inflection point; and wherein an axial distance between the aperture stop and the image-side surface of the tenth lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the tenth lens element is TD, a curvature radius of the image-side surface of the ninth lens element is R18, a curvature radius of the object-side surface of the tenth lens element is R19, an axial distance between the object-side surface of the first lens element and an image surface is TL, a maximum image height of the optical imaging system is ImgH, an Abbe number of the sixth lens element is V6, and the following conditions are satisfied: 0.60 < SD / TD < 1.20; − 1.20 < R 18 + R 19 / R 18 − R 19 < 1.30; 0.50 < TL / ImgH < 2.50, and 10.0 < V 6 < 40.0.. wherein the optical imaging system further comprises an aperture stop, the first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof, the image-side surface of the first lens element is concave in a paraxial region thereof, the second lens element has negative refractive power, the object-side surface of the second lens element is convex in a paraxial region thereof, the image-side surface of the second lens element is concave in a paraxial region thereof, the object-side surface of the third lens element is convex in a paraxial region thereof, the mage-side surface of the third lens element is concave in a paraxial region thereof, the object-side surface of the eighth lens element is convex in a paraxial region thereof, the image-side surface of the eighth lens element is concave in a paraxial region thereof, the ninth lens element has positive refractive power, the object-side surface of the ninth lens element is convex in a paraxial region thereof, the image-side surface of the ninth lens element is concave in a paraxial region thereof, the tenth lens element has negative refractive power, the image-side surface of the tenth lens element is concave in a paraxial region thereof, and at least one of the object-side surface and the image-side surface of the tenth lens element has at least one inflection point; and wherein an axial distance between the aperture stop and the image-side surface of the tenth lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the tenth lens element is TD, a curvature radius of the image-side surface of the ninth lens element is R18, a curvature radius of the object-side surface of the tenth lens element is R19, an axial distance between the object-side surface of the first lens element and an image surface is TL, a maximum image height of the optical imaging system is ImgH, an Abbe number of the sixth lens element is V6, and the following conditions are satisfied: 0.60 < SD / TD < 1.20; − 1.20 < R 18 + R 19 / R 18 − R 19 < 1.30; 0.50 < TL / ImgH < 2.50, and 10.0 < V 6 < 40.0..