The invention provides a device and method for producing propionic acid through an OXO process. The device comprises a reactor, a flash tank, a light component tower, a drying tower, a heavy componenttower, a stripping tower, an acetic acid removing tower, a propionic acid tower, an ethanol-rich methanol raw material pump, a catalyst mother liquor pump, a light component tower bottom pump, a drying tower bottom pump, a heavy component tower bottom pump, a stripping tower bottom pump and an acetic acid removing tower bottom pump which are connected through pipelines. The method comprises the following steps: adding a carbon monoxide raw material and an ethanol-rich methanol raw material into the reactor, and carrying out an OXO reaction under the action of a catalyst to generate a mixed solution of acetic acid and propionic acid; rectifying the mixed solution in an acetic acid rectifying area and a propionic acid rectifying area to obtain an acetic acid product and a propionic acid product respectively; pumping the catalyst into the reactor for recycling through the catalyst mother liquor pump in the flash tank,; and pumping light components such as methyl acetate, methyl iodide and water rectified from each tower top back into the reactor from the tower tops for recycling. According to the method, an ethanol-rich methanol product is used for producing acetic acid and propionicacid through the OXO process, so good economic benefits are obtained.