Abstract: There is a large amount of surplus high concentration carbon dioxide in soda plant using Hou′s process,which adopts intermittent fixed bed coal gas producer to produce semiwater gas with coal and coke as raw materials.Practice had testified high concentration carbon dioxide is very conducive to produce nano-sized calcium carbonate.If small-size synthetic ammonia devices can combine with new methanol coproducing technology of having fine de-sulfur devices，and nano-sized calcium carbonate producing technology,the traditional Hou′s soda technology can be developed to the new ‘green’ tetragenous coproduction technology,which can produce soda,ammonium chloride,nano-sized calcium carbonate,and methanol simultaneously. 