Novel chromophores containing s-triazine groups have been theoretically investigated for application of second-order nonlinear optical materials. Their first-order hyperpolarizabilities (beta (o)) and spectroscopic properties are calculated by employing AM1/finite field and ZINDO/S approaches, respectively. It is found that the modification of p-nitroaniline (PNA) or disperse orange 3 (DO3) with s-triazine group may produce compounds with short cut-off wavelength while retaining large nonlinear activities. The origin of such high beta (o) is analyzed based on the two-level model and effects of the character of substitute on the molecular hyperpolarizabilities are also discussed.