Abstract: In order to analyze the degree of influence of parameter on geo stress back analysis, the numerical simulation of rock mass parameters in the fluctuation range from minus 50 percent to plus 50 percent is carried out, observed the changes in the results of back analysis.The results of geo stress back analysis show that the greater the fluctuation of the parameter relative to the exact value, the higher the distortion degree of the back analysis result.The fluctuation of the known parameter with the back analysis results have a linear correlation; the accuracy of the modulus of elasticity E has the greatest impact on the inverse analysis results, the impact of Poisson's ratio μ is weaker than the former, the impact of the modulus of elasticity E' and Poisson's ratio μ' is relatively minor.