The invention relates to a horizontal-well physical simulation experiment device and an experimental method thereof. The horizontal-well physical simulation experiment device is composed of an injection system, a horizontal-well physical simulation device, a mining system and a data analysis and collection system. By adoption of an actual core, different ways of development of a horizontal well can be subjected to dynamic simulation, mining processes such as depletion-driven development, gas-injection huff and puff and displacement, and segmented perforating mining of the horizontal well can be simulated under the condition of high temperature and high pressure of an actual stratum; the actual core can be used in the study of affect of the different ways of the development of the horizontal well upon improvement of a mining rate, and provide of basis for numerical reservoir simulation and field development adjustment of the horizontal well.