Organic solar cells have achieved rapid development over the last few years, benefitting from the emerging of new non-fullerene acceptors (NFAs). The reported power conversion efficiency of OSCs has achieved over 18% up to now, however, the inferior stability issue restricts its commercialization, which stimulates the interest of scientists to explore it in-depth as well. Thus, we discuss the mechanisms of the instability in OSC devices, comprehensively summarize the progress of OSC stability in recent years and propose a series of solutions that improve the stability in this review. Although the highly-stable OSCs with extrapolated lifetime over several decades have been reported, the biggest drawback of them is the insufficient PCE. Thereby, investigating efficient OSCs with high-stability is required. We expect this review can provide some guidelines to address the instability of OSCs for feasible commercialization in the future.