Metastable ω phase in near-β titanium alloys is helpful for the precipitation of fine α precipitates, which can affect mechanical properties of these alloys. Therefore, researchers have studied the formation conditions, classification, transformation mechanism and diffraction patterns of the ω phase since it has been found. This article summarized the recent research results about embryonic ω, composition of ω and effects on α phase, which were researched by high resolution transmission electron microscopy and three-dimensional atom probe. On this basis, this paper expounds the current research difficulties and possible development direction.