A system or method for producing gasoline or dimethyl ether from natural gas via methanol includes: steam-reforming natural gas to generate reformed gas; synthesizing methanol from the reformed gas; synthesizing gasoline or dimethyl ether from the methanol; and at least one is selected from the group consisting of: pre-reforming natural gas prior to the steam-reforming; recovering carbon dioxide from flue gas generated in the steam-reforming; and preheating combustion air to be supplied to the steam-reforming by using synthesis heat generated in the synthesis of gasoline or dimethyl ether. In addition, an overall energy balance of the system is constructed by using heat recovery from flue gas generated in the steam-reforming, heat recovery from the reformed gas, synthesis heat generated in the synthesis of methanol, synthesis heat generated in the synthesis of gasoline or DME, and heat recovered in the pre-reforming, carbon dioxide recovering, or air preheating, respectively if selected.