Abstract: With regard to different natural water contents,the experimental research on the mechanical properties of Gypsum Breccia in natural and dried situations was conducted by use of the rock mechanics rigidity servo testing system(RMT-105B).The mechanical properties included the stress-strain curve,peak stress,Young’s modulus and poisson ratio of Gypsum Breccia.It was shown that the water content obviously affect the mechanical properties of Gypsum Breccia.The peak stress and Young’s modulus decreased exponentially,while the poisson ratio increased linearly with the increase of the water content in the natural situation.The variation of the mechanical properties,including peak stress,Young’s modulus and poisson ratio of Gypsum Breccia,was obvious.The peak stress and Young’s modulus were improved after drying.The mechanical properties were obviously affected by the natural water content.