The regioselectivities of 76 Diels-Alder reactions between unsymmetrical dienes and dienophiles were investigated by local softness and generalized local softness at atomic and chemical bond view,respectively,where the reactivity descriptors were calcu-lated by finite difference approximation and ABEEMoπ model.Based on local HSAB principle and matching criterion of local softness,reasonable explana-tion and prediction on regioselectivities of all reactions through ABEEMσπ model have been obtained,which are in agreement with the experimental results.Especially,atπ-bond level,while the 1-substituents of dienes were NH2,NMe2,and NEt2,because of the p-π conjugated effect between the lone pairs of N atom and the conjugated π-bond of the four double-bonded carbon atoms in diene,it made the dienophile not easy to approach diene by Manner A,hence,Manner B can forecast the ortho regioisomer as main product well,and Manner A cannot.As to the other reactions,both Manner A and Manner B can predict their regioselectivities.It can be seen that the ABEEMσπ model can take the effect of the chemical environment on the reac-tion reactivity into account richly,especially the system includes π-bbond and lone pairs.However,the results through the finite difference approximation are not reasonable.