Abstract: In this paper, we present a unified diagnostic method for nonlinear measurement error models. We show that the case deletion model is equivalent to mean shift outlier model. From this point of view, several diagnostic measures, such as Cook distance, Residuals, leverage measures are obtained. The local influence measure of nonlinear measurement errors model is also presented. An numerical example is given to illustrate the application of the diagnostics. The results of Zhao ＆ Lee （1995） are extended.