The invention relates to an energy-saving system for a power plant, which comprises a small-sized steam turbine and a draught fan, wherein the draught fan also serves as the booster fan of the power plant; and the small-sized steam turbine drives the draught fan. The energy-saving system also comprises a small-sized steam turbine steam inlet system, an open circulating cooling water system, a condensed water recovering system, a small-sized steam turbine shaft seal and lubrication system and a condenser vacuumizing system. The energy-saving system can considerably reduce the power consumptionrate of the power plant, contribute to the realization of the energy-saving and consumption-reducing goal of the power plant and reduce the production cost of enterprises.