We studied the characteristics of potassium ore in the 580m tunnel section of Mengyejing Potash Deposit, Yunnan by XRD, TEM EDS, and CT methods. The results of XRD and TEM EDS show that the main salt minerals are halite, sylvite, anhydrite, and magnesite. Sylvite exists in green grayish salt rock and gray green mud gravel salt rock. CT analysis also gives that halite shows circular and angular breccia in green grayish salt rock, and sylvite is banded or irregular shape along the edge of halite breccia. In the banded sylvite, we can see granular or lumpy sylvite, single granular sylvite is octahedral and cube, and lumpy sylvite is no specific form. The distribution characteristics of sylvite show that the formation of halite is earlier than sylvite, after the halite was destroyed by external forces, the deposition of sylvite is along halite fracture, and there may be multiple deposits.