Large mode area photonic crystal fibers (PCFs) have attracted much attention, owing to their applications in such as high power delivery, high power fibre amplifiers and fiber lasers. As an ideal candidate for fabricating mid-infrared fibers, chalcogenide glass possesses some unique advantages, such as high refractive indices (2.0-3.5), low photon energies (lower than 350 cm-1), tailorable compositions, and large infrared transmission window(from 1.0 to 20 μm). In this paper, we present a novel type of effectively single-mode chalcogenide glass Ge20Sb15Se65PCF with utra-large mode area as well as small confinement loss (lower than 0.1 dB/m for the fundamental mode, high confinement loss exceeding 2 dB/m for the higher-order mode at 10.6 μm).