The physical and chemical properties of metal nanomaterials are closely tied to their size and shape. A well-controlled synthesis protocol is needed to control over particle morphologies. Although the shape and size of metal nanostructures have been controlled by various pathways, such as soft templates and seed-mediated protocol method, most of the methods are involved with complicated multi-step synthesis. In this work, the morphology of palladium nanostructures, including nanorods, nanoparticles, and nanocubes, were well controlled by a simple one-step/one-pot polyol method in the presence of poly(vinylpyrrolidone) and KBr. A detailed study of the relationship between the morphology and controlling factors, such as reaction temperature, the concentration of metal precursor, PVP, reducing agent, and potassium bromide is presented. Well-controlled morphologies of Pd nanorods, nanospheres, and nanocubes are obtained via tuning these reaction parameters. The results from this work provide a basis for optimizing palladium nanocrystals growth through the simple onepot/one-step polyol method.