Crystallinity and morphology of perovskite absorber layers are important factors for influencing on the performance and stability of perovskite solar cells. Here, a perovskite-like metal formate (PLMF) material is firstly introduced as the scaffold into the perovskite precursor solution to improve the quality of perovskite films by effectively controlling the crystallization process in the course of the perovskite growth. The results show that the perovskite films with PLMF exhibit well-organized crystallinity and compact morphology, and therefore decreased grain boundaries which will notably reduce the electron-hole recombination and the defect points exposed to humidity. Finally, the photoelectricity properties have been significantly improved. The device with 3 mg ml(-1) PLMF achieves a power conversion efficiency of 19.17% with less hysteresis under AM 1.5G solar illumination, which shows a 16.53% increase than the pristine one (a power conversion efficiency of 16.45%). Importantly, the device with 3 mg ml(-1) PLMF displays excellent stability compared to pristine device under 40 +/- 5% and 70 +/- 5% relative humidity (RH) in the dark, maintaining about 85% and 60% of the original efficiency after about 1000 hat room temperature, respectively. This work offers a potential way by employing scaffold additive to improve the performance and stability of perovskite solar cells.