A Zr-based bulk metallic glass (BMG) in situ composite with a designed composition of Zr(60)Ti(14.67)Nb(5.33)Cu(5.56)Ni(4.44)Be(10) was prepared based on both modifying alloy composition and controlling solidification process. The composite contains high volume fraction of coarsen bcc beta-Zr(Ti, Nb) solid solution. The beta phase particles are short rod-like, worm-like, and nearly spherical in morphology rather than typical dendrite structure, their volume fraction and average diameter were estimated to be about 55% and 20 mu m, respectively. The composite displays a large fracture strain up to 22.3% under uniaxial compression at room temperature. The coarse beta phase and its high volume fraction were thought to be responsible for the excellent plastic deformability of the present composite.