07g-3-00820 is a K-type contact binary system with a period of 0.2269551 days. This extremely short period makes this system a rare target whose period is close to the empirical limit (0.22 days). R-c and I-c light curves of this binary were obtained using the 1.0 m reflecting telescope at Weihai Observatory of Shandong University. A high mass ratio of q = 1.300 +/- 0.006 and a low contact degree off = 5% +/- 1.5% were determined from a photometric study using the Wilson-Devinney method. The following parameters of this W-subtype shallow contact system were derived: M-1 = 0.621 +/- 0.072M(circle dot), M-2 = 0.807 +/- 0.093M(circle dot), R-1 = 0.634 +/- 0.036R(circle dot), R-2 = 0.710 +/- 0.037R(circle dot), L-1 = 0.270 +/- 0.037L(circle dot), and L-2 = 0.339 +/- 0.048L(circle dot). By analyzing the location of the two components on the mass-luminosity diagram, we provide a preliminary discussion on the properties and the state of evolution of this system. (C) 2017 Elsevier B.V. All rights reserved.