An output short-circuit protection method, a power management chip and a switched-mode power supply are disclosed. When current accumulation has occurred in a power transistor, the number of consecutive current pulses during which the current accumulation occurred is counted. Upon the number of consecutive current pulses reaches a preset value, a regulation interval spanning switching periods is triggered, for at least some of the switching periods, the leading-edge blanking time is shortened or cancelled. In this way, an excessively large current flowing through the power transistor is prevented. Compared with existing fault response measures for power management chips, restart of the power supply and adjustment of the system timing are not needed, allowing easier implementation. Further, the automatic restart during chip start up due to false triggering as found in the existing measures for power management chips is circumvented.