to evaluate the second-order nonlinear susceptibilities for a series of fulleropyrrolidine-tetrathiafulvalene(C60PY-TTF) dyads, C60PY, and C60PY-(CH=CH)n-TTF (n = 0-6). The equilibrium geometries, electronic structures, and UV-vis spectra of these C60PY-TTFs D-B-A dyads were determined by using ZINDO methods. On the basis of electronic spectra, we calculated the β for the dyads using the ZINDO-SOS expression, and found that these dyads have relatively large β. The calculated values of p are 48.78, 62.34, 97.90, 123.24, 183.78, 189.43, 193.45, 195.82 × 10-30 esu for C60PY and C60PY-(CH=CH)n-TTF (n=0-6), respectively, which shows the enhancing effect when TTF is introduced. The β significantly increases as n increases from 0-3; and it tends to be saturated in the end.