The invention relates to an automatic train operation (ATO) overspeed safety precautionary method for a train. The ATO overspeed safety precautionary method for the train comprises the steps that an original train automatic operation running speed curve is optimized and adjusted according to high speed limit and low speed limit; the actual running speed of the train which runs along the optimizedand adjusted train automatic operation running speed curve is tracked; when the situation that the train has the overspeed trend is confirmed, a brake gear is adjusted in real time according to the high speed limit value until the train runs according to the optimized and adjusted train automatic operation running speed curve again; and when the situation that the train is overspeed is confirmed,corresponding braking measures are taken on the train based on the comparative result between difference value of the train actual running speed and the safety protection curve and the critical threshold until the train continues to run along the optimized and adjusted train automatic operation running speed curve after the train actual running speed tends to the optimized and adjusted train automatic operation running speed curve. According to the ATO overspeed safety precautionary method for the train, multiple safety protection can be conducted on train overspeed in stages, so that train safety performance is more ensured.