With the aid of automatic direct method and Fourier synthesis, the author has determined the crystal structure of gorgeyite from Triassic evaporates in Sichuan. province. The structure parameter corrected by least squares method is R=0.084. structural analysis shows that gorgeyite is of monoclinic system, with space group C2/c,a=17.462(8)A,b=6.828(2)A,c=18.219(9)A，β=113.45(4)º,V=1992(1)A3. Z=4,，Dm=2.91 and Dx=2.90(3).The mean. lengths of S-O bonds of three sulfate tetrahedra are respectively 1.467, 1.464 and 1.478A.There exist three sets of calcium atoms, which have six-fold coordination with the mean. lengths of Ca-O boxids being respectively 2.516, 2.515 and 2.459A.Amdng these atoms, Ca1 lies alonrg the diced axis. The potassium atom has eight-fold coordination. The hydro- gen atom in the mineral has been located for the first time, and it is proved that the mineral contains one molecule of crystalline water rather than 1.5 molecules. Its crystal chemical formula should therefore be K2Ca5(SO4)6H2O.