Selective-controlled structure and shape of LaVO4 nanocrystals were successfully synthesized by a simple hydrothermal method without the presence of catalysts or templates. It was found that tuning the pH of the growth solution was a crucial step for the control of the structure transformation, that is, from monoclinic (m-) to tetragonal (t-) phase, and morphology evolution of LaVO4 nanocrystals. Further studies demonstrated that the morphology of the product had a strong dependence on the initial lanthanum sources. In the La (NO3)(3) or LaCl3 reaction system, pure t-LaVO4 nanorods with uniform diameters about 10 nm could be obtained. But when using La-2(SO4)(3) as the lanthanum source, we can get t-LaVO4 nanowiskers with broomlike morphology. The detailed systematic study had shown that a special dissolution-recrystallization transformation mechanism as well as an Ostwald ripening process was responsible for the phase control and anisotropic morphology evolution of the LaVO4 nanocrystals. As a result, the controlled synthesis of m-and t- LaVO4 not only has great theoretical significance in studying the polymorph control and selective synthesis of inorganic materials but also benefits the potential applications based on LaVO4 nanocrystals owing to the unusual luminescent properties induced by structural transformation.