In recent years, the study on the nonlinear least square adjustment has been conducted at home and abroad considering only the second-order terms of the expansion of Taylor's series. So far the study on the parameter's variance-covariance propagation in the nonlinear dynamic least square adjustment is still a subject to be studied. Therefore the parameter's variance-covariance propagation theory in the nonlinear dynamic adjustment is studied and its applied formulae are presented considering the third-order terms of Taylor's series expansion in the paper. It evidently enhances the scientism and precision of the parameter estimation in the nonlinear adjustment. Keywords: nonlinear dynamic adjustment, adjustment parameter, variance-covariance.