The density functional theory (DFT) B3LYP method based on the 6-31G level was employed to optimize the geometric structures of six amino coumarin derivatives. On the basis of obtaining stable molecular configuration, combined with time-dependent density functional theory (TD-DFT), the static second-order nonlinear optic polarizabilities (β) and the molecular electric spectrum were calculated by the same method. The results indicated that when amino substitute at the fourth position of coumarin the carbonyl show electron donating property which is a disadvantage for intramolecular charge transfer. When amino substitute at the third, fifth, sixth, seventh and eighth position of coumarin the carbonyl show electron with drawing property which makes the molecule form D-π-A configuration. And the third and seventh position can expand the conjugate system of molecule which can increase the βtot value of coumarin effectively.