Reconstructions and step structures on vicinal Bi:Si(001) surfaces are studied under various substrate temperatures and Bi coverages. The observed reconstructions are (2x1), (2x2), c(4x4), and (2x7) phases. For step distributions, alternative domain configurations with single layer steps are observed. The population ratios of A terrace to B terrace depend on the substrate temperatures. The observed reconstructions and step distributions are explained by the large size of the Bi atom compared with Si, the anisotropic stress tensor, and the local atomic structure in the S-B step.