Abstract: To realize the parameter identification and reduce the fault diagnosis cost of analog circuits, a methodology on fault location and parameter identification method for analog circuits based on the spectral radius and trace is proposed. Applying of matrix theory, the fault diagnosis model is established according to the correspondence between the fault device parameter variations and the change of the spectral radius and trace of response matrix of circuit under test (CUT). The fault detection, fault localization and parameter identification are integrated into one framework, so, the proposed method has the characters of low test cost and easy implementatiom. Experimental results show that this method is effective and the fault diagnosis accuracy and computational time overhead are satisfactory.