The invention relates to a method for treating waste water from a power plant and a system for realizing the same. The system comprises a pre-treatment system and an evaporative crystallizing system which are connected with each other; the pre-treatment system is connected to the waste water from the power plant, the majority of SS, heavy metals, Mg<2+>, F<-> and sulfate radicals in the waste water from the power plant are removed by coagulating sedimentation, and organic pollutants and ammonia nitrogen are also removed; the CaSO4 content in the waste water is adjusted to be far less than saturated concentration of the CaSO4, and the pH value is adjusted back to make partial CO3<2-> converted into HCO3<->; and the waste water treated by the pre-treatment system flows in the evaporative crystallizing system, by evaporation concentration, the dissolved solids in the waste water reach and exceed the saturated concentration to form salt crystal, and the solid-liquid separation is performed. The method has the advantages of effectively removing suspended matters, organic matters, fluorine and heavy metals in the waste water from the power plant, removing dissolved salt such as Ca<2+>, Mg<2+>, Cl<->, SO4<2-> and the like which can not be removed by the prior method for treating the waste water from the power plant, and basically meeting zero emission, and the treated waste water can be reutilized.