To date, antisolvent treatment has become one of the most important means to fabricate high efficiency perovskite solar cells (PSCs); however, the few reported antisolvents have not been analyzed on a uniform platform, and there is hitherto no clear reasoning in the choice of antisolvents toward high performance PSCs. Here, we study the role of the antisolvents in the nucleation kinetics of perovskite solutions and their residual influence on perovskite crystal growth, film formation, and device performance. Through X-ray diffraction analysis on the complicated double mixed perovskite, we qualitatively evaluate the impact of thermal annealing and antisolvent treatment (A.S.T.) on the phase composition and microstructure of the films. By using miscible antisolvents with high boiling point instead of immiscible low boiling point solvents, we obtain homogeneous and almost pinhole-free perovskite films. When using trilluorotoluene (TFT) to replace toluene and chlorobenzene as a novel antisolvent, we achieve a power conversion efficiency (PCE) of 20.3% under optimized device fabrication conditions with a composite perovskite as active layer. The conclusions from this study should assist in establishing reproducible fabrication processes and finding better antisolvent candidates for perovskite solar cells.