Phosphorus atomic chains, the narrowest nanostructures of black phosphorus (BP), are highly relevant to the in-depth development of BP-based one-dimensional (1D) nano-electronics components. In this study, we report a top-down route for the preparation of phosphorus atomic chains via electron beam sculpturing inside a transmission electron microscope (TEM). The growth and dynamics (i.e., rupture and edge migration) of 1D phosphorus chains are experimentally captured for the first time. Furthermore, the dynamic behavior and associated energetics of the as-formed phosphorus chains are further investigated by density functional theory (DFT) calculations. It is hoped that these 1D BP structures will serve as a novel platform and inspire further exploration of the versatile properties of BP.