Aim at design and understanding requirement of complex microstructure of titanium alloy, the microstructure of titanium alloy was further analyzed on the basis of conventional titanium metallography. It was pointed out that the microstructure of titanium alloy could be comprehended by two sides of morphology and structure. Based on the morphology of α phase, α phase could be distinguished to three kinds of First α, Secondary α and third α according to their transformation process. And then the three kinds of α phase were interpreted and defined. Lastly, taking two phase titanium alloy as an example, it was explained that how to design triple-modal microstructure using three kinds α phase, which will effectively coordinate the conflict of different mechanical properties on microstructure.