The Invention relates to an atmospheric-pressure acetylene carburizing furnace, comprises a reaction chamber, an acetylene intake duct, an exhaust gas duct, a control and metering apparatus, an exhaust gas measurement apparatus, and a computer controller. The computer controller calculates a total amount of carbon in the furnace and an enrichment rate of a workpiece, and adjusts an acetylene intake volume according to the calculation result until process requirements are met. The Invention realizes carburizing with acetylene under atmospheric pressure and reduces the usage costs while improving the equipment efficiency.