Although there have been extensive studies on the degradation of organic− inorganic hybrid perovskite (OIHP) films at the microscale, the microscopic degradation mechanism of the OIHP films under the effect of bias voltage and electric current has not been fully understood. We report in-situ measurements on the microscopic degradation process of solution-processed MA 0.4 FA 0.6 PbI 3 films using scanning tunneling microscopy. During the scanning process, hole-like structures appear inside the grain and at the grain boundaries, accompanied by the shrinking of the grain size. With a sufficiently large bias, direct fragmentation is observed. Furthermore, film degradations under passivation with dibenzo-24-crown-8 molecules are also studied, and a clear retardation of degradation process is observed. Our work provides in-situ observations of OIHP film degradation caused by local current and voltage, which are essential for understanding the microscopic degradation mechanism of metal halide perovskite films.