The effects of solution and aging process on the precipitation behavior and mechanical properties of Ti-15V-3Cr-3Sn-3Al titanium alloy were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that there are a large number of metastable martensite α" phases in the microstructure after solution treatment at 980℃×0.5h. After the aging treatment, the precipitates with different quantities and morphology are formed. With the increase of aging temperature or time, the number of precipitates increases, the morphology changes from irregular aggregation to acicular, and the size and spacing of precipitates also increase. During the aging process, a large number of nano dispersed α phases were precipitated, and the formation of the α/β phase interface hindered the dislocation movement, thus increasing the strength of the alloy. The more and smaller the precipitated phase is, the better the strengthening effect. The plasticity depends mainly on the distribution and number of precipitates on grain boundaries. The morphology of grain boundary α phase has a great influence on the plasticity of the material, and the continuous distribution of grain boundary α phase will seriously damage the plasticity of the material.