Abstract Isothermal annealing has been applied to a bulk metallic glass alloy, Zr50.7Cu28Ni9Al12.3. Nanocrystalline precipitates, mainly consisting of Ni3Zr and Ni42Zr58 phases, appear from the amorphous matrix when annealed at 743 K for different times, and the size of the precipitates increases with the increasing of the annealing time. High strain rate compression experiments were been also performed to test the fully amorphous and annealed Zr-based BMG samples. The dynamic fracture strengths of the tested samples firstly increase with the increasing of the annealing time, and reach the maximum value for the case of annealed for 90 min. A correlation between the microstructure and the dynamic mechanical properties was established in this study.