Abstract: Six flue-cured tobacco varieties (strains)were combined to form fifteen groups with diallel cross.The factors affecting the intrinsic quality of flue-cured tobacco F1, including main chemical component, yield characteristic, GCA between the parents and SCA between the crosses, were studied.The results showed that GCA and SCA were significantly different.It indicated that the character of quality and yield of flue-cured tobacco was controlled by both additive and non-additive genes.The analysis and comparison of GCA and SCA effects revealed that the GCA of different character from same parent varied significantly, and there was no direct relationship between GCA and SCA. The evaluation of breeding values of parents and the selection of cross combination should base on the variance analysis of GCA and SCA.