Principal Component Analysis ( PCA) can simplify the structure of database by replacing multidimensional parameters with relatively less comprehensive variables in order to ensure the minimum lost in initial data． In this paper，eighteen black soil samples from different sites were tested and thirteen distinctive indexes were chosen to evaluate the degeneration of black soil． By using principal component analysis，variables of thirteen dimensions can be diminished to six unrelated principal indexes． Analysis shows that the soluble salt content，Fulvic acids ( FA) and aggregation degree have a high weighing coefficient，indicating these three indexes are the major parts for the evaluation of black soil degradation． It also provides a new path to the degenerated black soil treatment in Northeast China．