Geometric structures of (1×1) and (1×2) Pt thin films on Pd(110) have been determined by dynamical low-energy electron-diffraction analysis. The (1×1) structure is found to exhibit relaxations in the first two interlayer spacings of Δd₁₂=-11.0% and Δd₂₃=6.6% at a Pt coverage of one monolayer, and relaxations of Δd₁₂=-6.6% and Δd₂₃=4.4% at two monolayers. As for the (1×2) structure, the top three layers are found to be Pt. The topmost layer is of the missing-row type, the second layer is slightly row paired (0.06 Å), and the third layer is significantly rumpled (0.23 Å). Relaxations in the first four interlayer spacings are found to be Δd₁₂=-9.5%, Δd₂₃=-8.0%, Δd₃₄=-7.3%, and Δd₄₅=2.2%. Except for a significantly less contracted first interlayer spacing, the (1×2) structure of the Pt film mimics the (1×2) structure of bulk Pt(110).