The invention provides a production method with a function of improving quality of fixed bed furnace coal gas. The production method comprises steps as follows: feed coal and a gasifying agent are subjected to a reaction in a gas-making furnace, and water gas is obtained; the adding amount of the feed coal is controlled until the temperature of a gas outlet of the gas-making furnace is 440-460 DEGC; the gasifying agent contains water vapor and oxygen; a flow ratio of the water vapor to the oxygen is 2.3 Kg/h:1Nm<3>/h. The water gas is prepared with the production method provided by the invention, so that content of CO2+H2 in a water gas product can be increased, content of CO2 can be reduced, and quality of the water gas product is obviously improved. Besides, with adoption of the production method, the use amount of steam for external supply can be reduced, scabbing is effectively prevented, and long-term stable operation of a water gas production system is guaranteed.