Abstract：The study of mechanical properties under changing effective stress is very important for gas reservoirs efficient development，but perfect experimental method and result are still not available. In order to get the mechanical characteristic of deuse-sandstone with the increasing of effective stress in gas reservoir development，the triaxial compression deformation experiment is performed on the GCTS–RTR–1000 triaxial rock testing system. Testing result shows that both the value of deformation modulus and Poisson¢s ratio increase with the increase of confining pressure. By comparing with the conventional experiment with constant confining pressure，the value of deformation modulus is higher than that of the constant confining pressure，while the value of Poisson¢s ratio under the condition of increasing confining pressure gets smaller.
