On the basis of basic morphological transforms and their combined modes， transient current signals can be extracted by use of morphological gradient with adaptive weighting. Meanwhile various kinds of additive noises are effectively suppressed by adaptive approach. Based on the different characteristics of spectrum analysis of extracted transients between the short circuit current and the inrush current， a new method of transformer protection is proposed. This method can avoid the symmetrical inrush current and non-periodic components can be sufficiently depressed. The results of dynamic simulation verify the feasibility of the proposed method.