Coarse macrograins have been observed in aerospace components for a high temperature near-a titanium alloy Ti60. The present work was inspired to understand the origin of coarse macrograin and examine how strain affects the macro/microstructure. Thus, thermomechanical processing was conducted in a þ b phase fifield to simulate industrial production. This alloy with a bimodal microstructure was isothermally pre-deformed at 1019 C and a constant strain rate of 0.1 s1 to height reductions of 15, 35, 55 and 75%. Heat treatment was conducted following deformation at 1024 C for 30 min. The results showed that coarse macrograins originated from inadequate recrystallization of prior b grains of initial billet. Deformation in the a þ b phase fifield does not form many new orientation b grains but slightly scatters b grain orientations around the orientations of big prior b grains in small strain samples. Each of different coarse macrograins corresponds to a family of prior b grains with similar crystallographic orientations with about 20 of spread, which is outlined by secondary a (as) plates having nearly parallel basal planes with similar crystallographic orientations. The size of macrograin decreases with increasing strain, which is consistent with the extent of recrystallization of prior b grain. These understandings can be applied to optimize processing routes for the control of fifinal macro/microstructure and properties in near-a titanium alloys.