The invention relates to a method for removing impurities from desulphurization 
gypsum of a power 
plant. The invention adopts a reversible conversion principle that dihydrate 
gypsum can be rapidly dissolved, re-crystallized and converted into alpha-
hemihydrate gypsum under the conditions that temperature is higher than or equal to 120 DEG C, pressure is higher than or equal to 0.15MPa, a pH value is 2.5-7 and an additive exists, and the alpha-
hemihydrate gypsum can be also rapidly converted into dihydrate gypsum when being cooled in a 
water environment. The method for removing the impurities from the desulphurization gypsum of the power 
plant comprises the following steps: sieving a 
raw material for filtering out large-particle impurities; preparing reaction 
slurry, and carrying out water type 
hot pressing reaction, so that dihydrate gypsum is rapidly converted into alpha-
hemihydrate gypsum; standing, and cooling, wherein alpha-hemihydrate gypsum in the 
slurry is converted into relatively large dihydrate gypsum particles; removing impurities to obtain a relatively pure gypsum material; carrying out water 
filtration to further remove small 
impurity particles and harmful soluble salt in gypsum; and obtaining 
slurry and a wet body or 
drying to obtain 
powder according to follow-up needs. The method for removing the impurities from the desulphurization gypsum of the power 
plant can be taken as a gypsum 
raw material purification process in preparation of 
calcium sulphate 
whiskers by virtue of the desulphurization gypsum, and can also be taken as a method for producing high-whiteness gypsum. The method for removing the impurities from the desulphurization gypsum of the power plant is simple, efficient and easy for 
mass production.