The interplay between the thermal transport property and the topological aspect is investigated in a spin-triplet chiral p-wave superconductor Sr2RuO4 with the strong two-dimensionality. We show the thermal Hall conductivity is well described by the temperature linear term and the exponential term in the low temperature region. While the former term is proportional to the so-called Chern number directly, the latter is associated with the superconducting gap amplitude of the gamma band. We also demonstrate that the coefficient of the exponential term changes the sign around Lifshitz transition. Our obtained result may enable us access easily the physical quantities and the topological property of Sr2RuO4 in detail.