To obtain the mechanical properties and stress-strain characteristics of traditional adobe and determine the mathematical expression of its variation relationship, a series of uniaxial compression tests and three-point bending tests were performed for molded adobe and compacted adobe. The mechanical properties of the two kinds of adobe were analyzed and compared by the compressive strength, flexural strength, failure mechanism, and stress-strain relationship. The results show that the test method for compression and bending of bricks can be applied to adobe. The compressive strength and flexural strength of compacted adobe are 3 times and 1.3 times of molded adobe, respectively, but the breaking energy of molded adobe is about 2.5 times higher than that of compacted adobe. In the early stage of compression, the stress-strain curve of compacted adobe has a concave section due to compaction of earth material, while this phenomenon has not been observed in molded adobe. The uniaxial compression constitutive model was proposed according to the stress-strain characteristics. This model shows a good correlation with the experimental data and may be applied to the numerical analysis of adobe structure.