Crack-free and transparent Sr2KNb5O15 (SKN) thin films have been synthesized by the chemical solution deposition method. A homogeneous and stable precursor solution was prepared via controlling the reaction of metal alkoxides. SKN precursor was found to be the complex alkoxide between Sr[Nb(OEt)6]2 and KNb(OEt)6 with high structural symmetry. SKN powders and thin films on fused silica substrates directly crystallized to the polycrystalline tetragonal tungsten bronze phase at 600 °C. Highly oriented SKN thin films with the tetragonal tungsten bronze phase were fabricated on MgO(100) and Pt(100)/MgO(100) substrates. Two crystal lattice planes of SKN were intergrown at an orientation of 18.5° on MgO(100). The dielectric constant of SKN thin films on Pt(100)/MgO(100) was about 590 at 20 °C at 1 kHz.