The embodiment of the invention discloses a high-pixel ultra-wide angle optical system which sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens from an object plane to an image plane along an optical axis, wherein a convex surface is formed on an object plane side of the first lens, a concave surface is formed on an image plane side of the first lens, and focal power of the first lens is negative; a convex surface is formed on an object plane side of the second lens, a concave surface is formed on an image plane side of the second lens, and focal power of the second lens is negative; the third lens is a biconvex lens, and focal power of the third lens is positive; a concave surface is formed on an object plane side of the fourth lens, a convex surface is formed on an image plane side of the first lens, and focal power of the first lens is positive; the fifth lens is a biconvex lens, and focal power of the fifth lens is positive; the sixth lens is a biconvex lens, and focal power of the sixth lens is positive; a concave surface is formed on an object plane side of the seventh lens, a convex surface is formed on an image plane side of the seventh lens, and focal power of the first lens is negative; and the eighth lens is a biconvex lens, and focal power of the eighth lens is positive. On the other hand, the embodiment of the invention further provides a camera module. The high-pixel ultra-wide angle optical system, disclosed by the embodiment of the invention, has high properties suchas large aperture, large viewing angle, high pixel, excellent athermalization and the like.