Abstarct: Because of the many uncertainties in the structures, using methods baxsed on knowledge of probability and statistics widely used in the analysis and Design and construction of the probability of failure has been found. In recent years the study of structures in the environment of uncertainty has been the focus of many researchers. In this study, the effects of uncertainty and change in the standard deviation between mass, stiffness and damping on the displacement of several typical linear behavior of structures with one, three, five and nine of degrees of freedom has been investigated. In order to observe the influence of structural variables with uncertainty, Dynamic analysis is compiled for each variable separately. The results showed a 53% increase in the mean response to the risk analysis is sighted.