In this study, the location, morphology and composition of the omega(o) phase, which transformed from B2 phase in Ti-45Al-8.5Nb-(W, B, Y) (at.%) alloy, were investigated by short-time heat treatments in an intermediate temperature range. The results showed that the characteristics of B2 -> omega(o) phase transformation differ with the reduction in temperature. Below the omega(o) solves, the B2 -> omega(o) phase transformation will take place within B2 area. There are existing two stages in the phase transformations during cooling from 850 to 700 A degrees C. When the temperature is high (850 A degrees C), granular omega(o) populated along the dislocations existing in B2 phase and B2 grain boundaries, due to higher energy and the enrichment of Nb element at the B2/gamma boundaries. It is worth noting that only two omega(o) variants nucleate at 850 A degrees C. With the decrease in temperature, the nucleation sites of omega(o) phase would be migrated from the B2 boundaries to the inner area. At the temperature of 700 A degrees C, four omega(o) variants with different orientations nucleate homogenously within B2 grain. The ordered omega(o) formation process of Ti-45Al-8.5Nb-(W, B, Y) alloy during cooling was postulated in this study.