It is of great difficulty to create new antimonite with second-harmonic-generation (SHG) intensity larger than 6 times of KDP. In this study, a polyfluoroantimonite strategy has been proposed to explore fluoroantimonites with large nonlinear optical (NLO) coefficient. Under the coorpration of chemical (highly asymmetric π-conjugated organic amine) and physical (viscous reaction medium ethylene glycol) methods, two novel polyfluoroantimonites, namely, (3PC)2(Sb4F14) and (3AP)2(Sb4F13), have been achieved. Interestingly, these two structures contain two new polyfluoroantimonite groups respectively, an isolated (Sb4F14)2− four-member polyhedral ring and an infinite [Sb4F13]■(-@∞) helical chain. More importantly, the polar (3AP)2(Sb4F13) displays a strong SHG intensity of 8.1 × KDP, a large birefringence of 0.258@546 nm and a high laser-induced damage threshold (LIDT) value of 149.7 MW/cm2. Theoretical calculations indicated its strong SHG effect stems from the synergistic effect of helical [Sb4F13]■(-@∞) polyfluoroantimonite chain and π-conjugated 3AP+ cation, with contribution ratio of 48.93% and 50.77% respectively. This work provides a new approach for design and synthesis of high-performance fluoroantimonites.