This paper discusses the uniqueness of displacement back analysis for circular roadways in viscoelastic rock masses.Taking the Kelvin model as the research subject,based on the analytical solution of displacement for circular roadways,the uniqueness of displacement back analysis for rock mass parameters is studied using parameter identifiability conditions.The results show that regardless of the number of measured displacement points,it is not possible to uniquely back analyze all rock mass parameters with only one known parameter.At least 2 parameters must be known in order to potentially back analyze the remaining parameters;as more parameters become known,the identifiability of each parameter gradually improves;whether the vertical and horizontal ground stresses are equal and whether they are set to zero as known conditions have a significant impact on the back analysis results;properly reducing the number of parameters to be inverted has a significant effect on enhancing the uniqueness of the back analysis results;among all parameters,the ground stress exhibits the best identifiability,followed by elastic modulus,while Poisson’s ratio and viscosity coefficient show the poorest identifiability.