As the major rock-forming mineral in Pobei mafic-ultramafic complex, clinopyroxene is distributed in almost every rock phase. In order to find out the nature, evolution and tectonic setting of magma, the authors analyzed chemical compositions of clinopyroxene by means of EPMA and LA-ICPMS. The results demonstrate that cliopyroxene is characterized by SiO₂(51.05%～54.00%), MgO(13.95%～17.64%), CaO(19.87%～23.56%), FeO(3.44%～6.58%), TiO₂(0.13%～1.36%), Al₂O₃(2.17%～4.21%), Na₂O(0.17%～0.50%), and Cr₂O₃(0.01%～1.27%). Combined with other data available, the authors believe that the magma was assimilated when it experienced fractional crystallization.