The invention discloses a high-temperature and high-pressure testing platform internally provided with a flexible reaction chamber. The high-temperature and high-pressure testing platform mainly comprises the flexible reaction chamber, an outer titanium alloy chamber, a pressurizing pump and a pressure adjusting device, wherein the flexible reaction chamber and the outer titanium alloy chamber are arranged on the same axis. The flexible reaction chamber is formed by welding a titanium foil and a pure titanium material; the inner part of the reaction chamber and the outer chamber are separated by using a gold sealing ring; pure water is fully filled between the flexible reaction chamber and the outer titanium alloy chamber; the inside temperature and the inside pressure are raised through a heating device; when the pressure is raised to pre-set pressure, the pressure adjusting device is started to keep the pressure constant. A sampling pipe is connected with the flexible reaction chamber to realize the real-time sampling; after sampling, the outer pressure of the flexible reaction chamber is not changed so that the inside pressure is not changed, so as to guarantee that a reaction environment inside the flexible reaction chamber is not changed after the sampling. The flexible reaction chamber not only utilizes a high-temperature-resisting and corrosion-resisting performance of a titanium foil material, but also guarantees the flexibility of deformable compression. The testing platform disclosed by the invention is suitable for simulating water rock reaction under high temperature and high pressure; meanwhile, the testing platform is convenient for real-time sampling and analysis.