Existing greenhouses have generally constructing about a span of 6m~8m. However, recently greenhouses are being required a longspan over 8m for land using efficiency and convenience of farming equipment. In this study, longspan specimens of 10m have designed, and symmetric loading test assumed heavy snow has performed with variable of tension-tie strengthening. Also, the tests of a eccentric snow loading by the sun and wind were conducted and load-deflection relationships were compared for the cases of reinforced with tie and without tie.