The classical NVESD view-field searching for target detection probability couldn′t reflect signal-to-clutter ratio (SCR) influence on detection. The wavelet multi-scale edge detection is adopted to emulate vision system,confining probability of edge (POE) with the root meam square (RMS) of Reynold identical equations which is revised by wavelet multi-resolution analysis,to derive a new algorithm based on wavelet scale. Then the maximum probability was utilized to process a target and its backgrounds detection,so as to derive the maximum probability for target pattern identification. The SCR calculation was introduced into the infrared target detection algorithm to derive the prediction for target detection,classification and identification at high,mediate and low SCR conditions,so that the relation between infrared target detection and SCR is revealed.