The invention belongs to the technical field of uranium mining and metallurgy, and relates to a pretreatment method for mud uranium ores, in particular to a pretreatment method of mud uranium ores rich in gypsum and carbonate minerals. According to the pretreatment method for the mud uranium ores, firstly coarse-grained ores rich in the gypsum are separated, and the coarse-grained ores can recycle uranium through a dump leaching method, the ores grinding cost can be saved and the reagent consumption when fine-grained ores are leached through a alkaline process can be reduced. The fine-grained ores rich in the carbonate minerals are divided into two parts of high-carbonated uranium ores and low-carbonated uranium ores through a flotation method; the uranium can be recycled through subtractive leaching and acid leaching in the follow-up leaching, the reagent consumption can be saved, and the leaching rate is improved.