A lens comprising: a bottom surface; a light incident surface configured to receive light emitted by the light source; a first convex curved surface used as a first light exiting surface; a first ringy inclined plane used as a second light exiting surface; a second convex curved surface used as a third light exiting surface, wherein the first light exiting surface, the second light exiting surface and the third light exiting surface are successively connected from top to bottom and from inside - central to outside - peripheral; the second light exiting surface contacts with the third light exiting surface to form a first step, the light incident surface is an inner concave cambered surface, tangent lines of the generatrixes of the inner concave cambered surface intersect a rotation axis therein to form first included angles; the first light exiting surface is a convex curved surface with a central recess, tangent lines of the generatrixes of the convex curved surface with central recess intersect a rotation axis therein to form second included angles; the second light exiting surface intersects the bottom surface to form a third included angle; the third light exiting surface is an outer convex curved surface, tangent lines of the generatrixes of the outer convex curved surface intersect a rotation axis therein to form fourth included angles; a second ringy inclined plane used as a fourth light exiting surface; a third convex curved surface or a circular table surface used as a fifth light exiting surface; wherein the fourth light exiting surface contacts with the third light exiting surface, the fourth light exiting surface contacts with the fifth light exiting surface to form a second step; characterized in that the angle between the fourth light exiting surface and the bottom surface is less than the angle between the second light exiting surface and the bottom surface; when the fifth light exiting surface is an outer convex curved surface, the values of the angles between tangent lines of the generatrixes of the outer convex curved surface and a rotation axis therein increase from top to bottom; the third included angle is less than 45°. a bottom surface; a light incident surface configured to receive light emitted by the light source; a first convex curved surface used as a first light exiting surface; a first ringy inclined plane used as a second light exiting surface; a second convex curved surface used as a third light exiting surface, wherein the first light exiting surface, the second light exiting surface and the third light exiting surface are successively connected from top to bottom and from inside - central to outside - peripheral; the second light exiting surface contacts with the third light exiting surface to form a first step, the light incident surface is an inner concave cambered surface, tangent lines of the generatrixes of the inner concave cambered surface intersect a rotation axis therein to form first included angles; the first light exiting surface is a convex curved surface with a central recess, tangent lines of the generatrixes of the convex curved surface with central recess intersect a rotation axis therein to form second included angles; the second light exiting surface intersects the bottom surface to form a third included angle; the third light exiting surface is an outer convex curved surface, tangent lines of the generatrixes of the outer convex curved surface intersect a rotation axis therein to form fourth included angles; a second ringy inclined plane used as a fourth light exiting surface; a third convex curved surface or a circular table surface used as a fifth light exiting surface; wherein the fourth light exiting surface contacts with the third light exiting surface, the fourth light exiting surface contacts with the fifth light exiting surface to form a second step; characterized in that the angle between the fourth light exiting surface and the bottom surface is less than the angle between the second light exiting surface and the bottom surface; when the fifth light exiting surface is an outer convex curved surface, the values of the angles between tangent lines of the generatrixes of the outer convex curved surface and a rotation axis therein increase from top to bottom; the third included angle is less than 45°.