Tungsten trioxide hydrate (WO₃路0.33H₂O) films with different morphologies were directly grown on a fluorine doped tin oxide (FTO) substrate. With the directing effect of a seed layer, WO₃路0.33H₂O thin films composed of nanosheet structures could be selectively synthesized. The effect of urea was also discussed in this paper. The crystal-seed-assisted film grown with urea as a capping agent exhibits efficient electrochromic performances.