A wide-angle lens, comprising a first lens group, a diaphragm and a second lens group disposed in sequence from an object side to an image side, the first lens group comprising, in sequence from an object side to an image side: a first lens having a negative refractive power, an object side surface of the first lens is a convex surface and an image side surface is a concave surface; a second lens having a negative refractive power, an object side surface of the second lens is a convex surface and an image side surface is a concave surface; a third lens having a positive refractive power, both of an object side surface and an image side surface of the third lens are convex surfaces; the second lens group comprising, in sequence from an object side to an image side: a fourth lens having a positive refractive power, and an image side surface is a convex surface; a fifth lens having a positive refractive power, both of an object side surface and an image side surface of the fifth lens are convex surfaces; a sixth lens having a negative refractive power, both of an object side surface and an image side surface are concave surfaces; a seventh lens having a positive refractive power, both of an object side surface and an image side surface are convex surfaces; wherein the diaphragm is disposed between the first lens group and the second lens group; the wide-angle lens satisfies the following relationship: H2/G2R2 < 1.8; where, H2 is an effective diameter of the image side surface of the first lens; G2R2 is a curvature radius of the image side surface of the first lens; and wherein the wide-angle lens is characterized in that an object side surface of the fourth lens is a flat surface, and in that the diaphragm is attached to the object side surface of the fourth lens. a first lens having a negative refractive power, an object side surface of the first lens is a convex surface and an image side surface is a concave surface; a second lens having a negative refractive power, an object side surface of the second lens is a convex surface and an image side surface is a concave surface; a third lens having a positive refractive power, both of an object side surface and an image side surface of the third lens are convex surfaces; the second lens group comprising, in sequence from an object side to an image side: a fourth lens having a positive refractive power, and an image side surface is a convex surface; a fifth lens having a positive refractive power, both of an object side surface and an image side surface of the fifth lens are convex surfaces; a sixth lens having a negative refractive power, both of an object side surface and an image side surface are concave surfaces; a seventh lens having a positive refractive power, both of an object side surface and an image side surface are convex surfaces; a fourth lens having a positive refractive power, and an image side surface is a convex surface; a fifth lens having a positive refractive power, both of an object side surface and an image side surface of the fifth lens are convex surfaces; a sixth lens having a negative refractive power, both of an object side surface and an image side surface are concave surfaces; a seventh lens having a positive refractive power, both of an object side surface and an image side surface are convex surfaces; wherein the diaphragm is disposed between the first lens group and the second lens group; the wide-angle lens satisfies the following relationship: H2/G2R2 < 1.8; where, H2 is an effective diameter of the image side surface of the first lens; G2R2 is a curvature radius of the image side surface of the first lens; and wherein the wide-angle lens is characterized in that an object side surface of the fourth lens is a flat surface, and in that the diaphragm is attached to the object side surface of the fourth lens. H2/G2R2 < 1.8; where, H2 is an effective diameter of the image side surface of the first lens; G2R2 is a curvature radius of the image side surface of the first lens; and wherein the wide-angle lens is characterized in that an object side surface of the fourth lens is a flat surface, and in that the diaphragm is attached to the object side surface of the fourth lens.