The development of nano-sized titanosilicate zeolites with hierarchical structures is crucial in promoting the efficient epoxidation of alkenes. In the present work, nano-sized hierarchical Ti-β (*BEA) zeolites with high crystal yield are prepared by a one-pot nanoseed-assisted approach. The influence of seed size on the resultant Ti-β zeolites is investigated by complementary characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption/desorption, UV-vis diffuse reflectance spectroscopy (DRS), and UV Raman spectroscopy. The possible process for the formation of hierarchical Ti-β nanocrystals with the assistance of nanoseeds in the synthesis gel is proposed. Consequentially, the nano-sized hierarchical material prepared by the nanoseed-assisted method shows excellent mass transportation and accessibility to active sites by reducing particle size and constructing hierarchical porosity, hence showing a remarkably enhanced catalytic activity and selectivity in the epoxidation reaction of alkenes. This work will shed light on the efficient preparation of nano-sized titanosilicate zeolites.