Abstract: To study the influences of the specific climate in the northeast areas of China on the slaking characteristics of mudstone, the effects of freeze-thaw and drying-wetting cycles on the slaking characteristics of mudstone are analyzed based on a case study of Haizhou open pit mine in Fuxin, Liaoning. A series of experiments are carried out under the freeze-thaw and drying-wetting cycles, and the effects of the natural environmental factors on the change of the mudstone are discussed. The electrical conductivity and pH of the soak solution are recorded, and the changes of slaking ratio, porosity and water absorption rate of mudstone samples in slaking process are analyzed as well. Through analysis of the X-ray diffractometer (XRD) and fluorescence spectrum system, the mineral & chemical composition of mudstone is made clear. The test results show that, compared with the drying-wetting effects made in the natural condition, the freeze-thaw cycles can make noticeable effects on the mudstone which are mainly caused by the porosity and water absorption, rather than the dissolution of soluble salt. It is of great significance to take into account the effects of freeze-thaw cycles on the slaking characteristics of mudstone in the engineering construction in the northeast area of China .