The invention relates to an eyepiece optical system with large field angle and high image quality and a head-mounted display device. The eyepiece optical system with large field angle and high image quality comprises a first lens group and a second lens group, which are coaxially and sequentially arranged along an optical axis from a human eye to an image source and satisfy a certain focal length relationship. The first lens group is composed of a first lens near the human eye and a second lens far away from the human eye. The second lens group is composed of one or two lenses. The first lens is biconvex. The optical surface, near the human eye, of the second lens is concave towards the human eye, and is aspheric. The spacing between the first lens and the second lens, the focal length relationship between the lenses in the second lens group and the materials of the lenses satisfy a certain relationship. The second lens group further includes a fourth lens and a fifth lens arranged separately. The eyepiece optical system of the invention has the advantages of large aperture, large field of view, high resolution, low distortion, small size, and the like, and is suitable for head-mounted displays and similar devices.