The stress-strain curve of (α + β) Ti-8Mn alloys was measured, and α and β titanium alloys, whose compositions were close to those of α and β phase in the dual phase titanium alloy (Ti-8Mn) were designed. According to the above mentioned design, the stress-strain curve of Ti-8Mn alloy was calculated and compared with measuring one. The results show that they are in good agreement, which indicates that the model established is available. According to the model above, the distributions of stress and strain were simulated along different sections when only one α grain was distributed in the β crystal. And the result illustrates that the minimum stress exists at the center of α crystalline grain, while the maximum stress exists at the crystal boundary. The stress decreases gradually with increasing of the distance away to dual sides, while the distribution of strain is in opposition to the stress distribution.