The utility model discloses a cooling self-starting device for a power distribution transformer. The cooling self-starting device comprises a current transformer, an intermediate relay, an inverse time limit overcurrent relay and a micro circuit breaker for controlling starting and stopping of a fan, wherein the current transformer is arranged at a load wire inlet end; a coil of the inverse time limit overcurrent relay is connected in series between the output ends of the current transformer; an often-open contact of the inverse time limit overcurrent relay is connected in series with a coil of the intermediate relay to form a first branch circuit; an often-open contact of the intermediate relay is connected in series with the fan to form a second branch circuit; the first branch circuit and the second branch circuit are connected to a control loop of the micro circuit breaker after being connected in parallel with each other. According to the cooling self-starting device for the power distribution transformer, the inverse time limit overcurrent relay is used for monitoring a working condition of the power distribution transformer, and the inverse time limit overcurrent relay is cooperated with the intermediate relay to control the starting and the stopping of the fan, so that the work of the fan can be changed according to the working condition of the power distribution transformer; the cooling self-starting device wholly performs operation as required, and energy waste caused by manual operation is avoided.