The invention provides a double-turbine steam thermodynamic system with a regenerative steam extraction function. The double-turbine steam thermodynamic system comprises a large steam turbine, a small steam turbine and a regenerative cycle unit. The regenerative cycle unit comprises one or a plurality of high-pressure heaters, one or a plurality of medium-pressure heaters, one or a plurality of low-pressure heaters and two deaerators, and a water circulating pipeline is communicated with a boiler via the low-pressure heaters, the low-pressure deaerator, the medium-pressure heaters, the high-pressure deaerator and the high-pressure heaters sequentially. The double-turbine steam thermodynamic system with the regenerative steam extraction function has the advantages that medium-pressure cylinders of the large steam turbine do not need to be provided with steam extraction openings for regenerative steam extraction owing to the double-deaerator structure, medium-pressure cylinder structures of the large steam turbine are greatly simplified, the axial dimension of an integral unit is reduced, and the through-flow capacity of the large steam turbine is improved; and sufficient flow and sufficient power for the small steam turbine can be guaranteed, a complicated logic balance system for the power of the small steam turbine is omitted, and accordingly the integral system is simple and reliable.