The AST3 project consists of three large field of view survey telescopes with 680mm primary mirror, mainly for observations of supernovas and extrasolar planets searching from Antarctic Dome A where is very likely to be the best astronomical site on earth for astronomical observations from optical wavelength to thermal infrared and beyond, according to the four years site testing works by CCAA, UNSW and PRIC. The first AST3 was mounted on Dome A in Jan. 2012 and automatically run from March to May 2012. Based on the onsite winterization performance of the first AST3, some improvements such as the usage of high resolution encoders, defrosting method, better thermal control and easier onsite assembly et al were done for the second one. The winterization observation of AST3-2 in Mohe was carried on from Nov. 2013 to Apr. 2014, where is the most northern and coldest part of China with the lowest temperature around -50°. The technical modifications and testing observation results will be given in this paper. The third AST3 will be optimized from optical to thermal infrared aiming diffraction limited imaging with K band. Thus the whole AST3 project will be a good test bench for the development of future larger aperture optical/infrared Antarctic telescopes such as the proposed 2.5m Kunlun Dark Universe Survey Telescope project.