Absorption spectroscopy measurements of gas molecules in high-temperature and high-pressure environments are crucial for studying absorption line parameters and laser absorption spectroscopy-based combustion diagnostics. Because of the lack of high-temperature and high-pressure measurement environments, this work established an experimental setup for spectroscopy measurements in the temperature range of 25~1 000 ℃ and pressure range of 0~100 atm for the first time. The absorption path length was 20 cm, and the temperature uniformity within the path length was better than 5%. The feasibility of the experimental setup was demonstrated by measuring H2O absorption spectroscopy under conditions of 1 000 ℃ and 75 atm using a swept laser whose wavelength can cover 7 370~7 450 cm-1. The measured broadband spectra were by the simulated spectra based on the HITRAN database. This experimental setup can provide stable environments for the research of spectroscopic parameters of different molecules (H2O, CO2, etc.) at elevated pressures and temperatures and has high potential to promote the development of absorption spectroscopy-based combustion diagnostics.