Abstract: The Northern Xinjiang is characterized by a large number of Permian mafic-ultramafic complexes with magmatic Cu-Ni sulfide mineralization in different tectonic unit.The identification of the top and bottom of these Cu-Ni sulfide-bearing mafic-ultamafic intrusions,a worldwide problem,is significant for the blind ore exploration.According to the outcrop area and lithofacies,these complexes can be divided into large complex(>18-40 krn²),small complex massif(1-5 km²)and simple rock-body(< 0.1 km²),The three types differ in body size,occurrence,Iithofacies,the ratio of mafic and ultramafic bodies,ore-bearing lithology,space distribution of orebody and the ratio of Cu/Ni in orebody.The abovementioned essential features of the complexes and mineral grain,alteration degree,basalt and diabase coeval with mafic-ultramafic intrusions,can determine the relative erosion degree of the deposits synthetically.The relative erosion degree in combination with the regional element geochemical and geophysics anomalies,are the effective measures to evaluate the Cu-Ni mineralization potential in mafic-ultramafic complexes.Mafic dykes,small intrusion,ultramafic outcrop in large mafic-ultramafic complex,strongly altered mafic-ultramafic intrusive rocks.gravity and magnetic anomaly zone superimposed geochemical anomalies,are the important target for finding small intrusion with large scale magmatic CuNi sulfide deposits.