Crack‐free, dense, and transparent Pb0.6Ba0.4Nb2O6 (PBN60) thin films have been prepared by a sol‐gel method with metal alkoxides and metal acetate. A homogeneous and stable precursor solution was obtained from Ba metal, Pb(CH3COO)2, and Nb(OEt)5 in 2‐methoxyethanol. PBN60 powder crystallized to the hexagonal phase at 600°C and then completely transformed to the orthorhombic phase of the tungsten bronze structure at 1250°C. The hexagonal phase was formed on SiO2 glass, MgO(lOO), and sapphire(R) substrate at 600°C, while the orthorhombic phase was only on a sapphire(C) substrate. Orthorhombic PBN60 films with c‐axis preferred orientation were successfully synthesized on sapphire(C) substrates at 600°C.