（1.Liaoning Research Institute of Pomology，Xiongyue，Liaoning 115009；2.College of Horticulture，Shenyang Agricultural University，Shenyang，Liaoning 110161）
By using the relational grade analysis of gray system theory，the relational gray coefficient and grade on leaf net photosynthetic rate (Pn) of three apricot cultivars (‘Shajinhong’,‘Mono’‘Shanxing’,which were cultivated under normal and drought conditions) and main ecological factors(Gs，Ci，Tr，Tleaf，Ca，H2O concentration of atmosphere，RH，PAR) were analyzed.The results showed that under normal condition,the factor which seriously influenced leaf Pn of apricot was Tr，PAR and Tleaf.Under drought condition,the factor which seriously influenced leaf Pn of apricot was Ca，Gs and Tleaf.There were different relational grade ranks in different cultivars，and for the same cultivar，there were different relational grade ranks under different condition，integrated cultural practices should be made on cultivar characteristics and developmental stage.