Abstract: The geometries of a series of chiral helicenes were optimized using density functional theory B3LYP method at the 6-31G(d,p)level. Based on the obtained stable molecular configuration, the ZINDO-SOS method was adopted to calculate the second-order nonlinear optical coefficients of these molecules.From the results,the second-order nonlinear optical coefficients βμ  were not proportional to the ground state dipole moments. The second-order nonlinear optical coefficients of the helicenes were spatial arrangement dependent of the substituents. The second-order nonlinear optical responses were enhanced significantly when the orientions of the double charge transfer are appropriate.