The invention relates to a method of using active persulphate for processing difficult-biodegradability organic waste water, which is characterized in that persulphate is firstly thrown into a reaction container containing organic waste water, after mixing and dissolving, the mixture is placed into a microwave generator with the frequency of 2450 MHz and the power of 800 W to be radiated for several minutes to be completed, wherein the biodegradability index BOD5 / COD of the organic waste water is lower than 0.2, and the mol ratio of the throwing amount of the persulphate and the organic matter in the organic waste water is 10:1 to 50:1. The persulphate includes peroxy-monosulphate and peroxydisulphate. To improve the degrading efficiency of the organic waste water, before using the microwave active persulphate for processing the difficult-biodegradability organic waste water, a catalyst is added, wherein the ratio of the weight of the catalyst and the volume of the organic waste water is 0.1 to 1, and the added catalyst is active carbon, and the like. The invention has the characteristics of short processing time, no secondary pollution and small occupied land area of the equipment, and can obtain an excellent processing effect on the difficult-biodegradability organic waste water.