By the methods of sampling soil profiles which A,B,and C represent humus horizons,illuvial horizons,and parent materials horizons respectively,relationships between the activities of soil enzymes (which include catalase,invertase,protease,and acid phosphatase) and plant species diversity in three secondary successional plant communitites of forest ecosystem in Mt.Jinyun were studied in this paper.Results showed that different degree′s correlations existed between soil enzymic activities and plant species diversity indice (PSDI) which included Shannon-Wiener H′ index and Hill′s species diversity indice family \%N A\%,moreover,the degree of correlation depended on the horizon of soils,the type of enzymes,and the life form of plants (i.e.,tree,or shrub or grass).The degree of correlation between PSDI and soilenzymic activities decreased by the orders of A→B→C.The most significant correlation with PSDI was the activity of soil catalase,and in turn,was the activity of soil invertase,On the whole,the correlation between soil enzymic activities and tree layer′s PSDI was the most evident.Tree layer′s PSDI were positively and significantly (P<0.05) or very significantly (P<0.01) correlated with the activities of catalase and invertase of A and B horizons,and of protease and acid phosphatase of A horizons.Grass layer′s PSDI were also positively and significantly (P<0.05) correlated with the activities of catalase and invertase of A horizons.Shrub layer′s PSDI were not significantly correlated with soil enzymic activities.