The gravitation level style rock rheology test machine was developed by the authors. Its scale-up ratio is 120 and the error is less than 0.4%. Load may keep stable in any time(e.g. long-term) to meet the requirements of rock rheology test. The rheology properties and stress effects of creep moduli under creep conditions were experimentally studied by using specimens of red sandstone under step load with the gravitational style rock rheology test machine. The differences between axial and lateral creep properties and long-term strength of rock were specially observed and analyzed. The experimental result shows that the lateral stress threshold of the second creep stage is less than that of axial stress threshold. There is an obvious accelerated stage in the lateral creep course；and the accelerated stage in lateral creep course appears earlier than that in the axial creep course；but the third stage of the axial creep is not obvious and the rock specimen will be damaged as soon as the third stage appears. According to the experimental result，the long-term strength of rocks should be determined in terms of lateral stress threshold of second creep stage of the rock；so the determined long-term strength value is less 19%–35% than that determined in terms of axial stress threshold of the second creep stage of the rocks. There is an important directive meaning for this result to account for the creep stability in the geotechnical engineering fields.