Disclosed is an eyepiece optical system with a large field-of-view angle, and a head-mounted display apparatus. The eyepiece optical system comprises a first lens group (G1) and a second lens group (G2) which are arranged coaxially and successively along an optical axis from a human eye to an image source and meet a certain focal length relationship. A distance (D12) between the first lens (L1) and the second lens (L2), a focal length relationship of lenses within the second lens group (G2) and the material properties of various lenses meet a certain relationship. The eyepiece optical system has the advantages of large aperture, large field-of-view, high resolution, low distortion, and small size, etc., and is suitable for a head-mounted display and similar apparatuses.