The utility model discloses a high-concentration carbon monoxide isothermal transformation system and solves the problems of long process, large system resistance drop and short catalyst service life existing in an existing transformation system. The technical scheme adopted by the utility model is that the high-concentration carbon monoxide isothermal transformation system comprises a raw material gas separator, a raw material gas filter, a shell side of an air cooled shift reactor, a first water cooled shift reactor, a tube side of the air cooled shift reactor and a cooling recovery system, wherein the first water cooled shift reactor is provided with a steam pocket for by-product steam. The high-concentration carbon monoxide isothermal transformation system is simple in process flow, reliable in system, small in adverse methanation reaction, short in process flow, small in system resistance, long in catalyst service life and low in equipment investment and running cost.