long-range charge transfer organic compounds are remarkable for having very large hyperpolarizabilities and thus improved nonlinear optical (NLO) properties. p-nitroaniline (pNA) is known as a prototypical NLO organic material. The question answered in this work is the NLO properties of pNA will be improved by introducing an extended π-conjugation chain between the phenyl ring and the two NH2/NO2 terminal? By means of sophisticated ab initio/MP2 calculations, new derivatives of pNA with an extended π-conjugation have been designed by introducing –(CH=CH)nNH2 or –(CH=CH)nNO2 (n = 1–5) chain into pNA. The results indicate that introducing such chains results in smaller energy gaps and transition energies, which lead to a significant improvement in the hyperpolarizability (β_0). The novel pNA derivatives exhibit larger β_0 amplitudes up to 4.67 x 104 au, which is 27-fold greater than that of pNA. Moreover, with increasing the β_0 amplitude, the –(CH=CH)nNO2 chain beats the –(CH=CH)nNH2 chain. It is hoped that this study can provide a help for designing higher performance NLO materials based on pNA.