The present invention is automatic decoupling mechanism for railway freight car, and automatic decoupling mechanism is especially suitable for decoupling No. 13 standard coupler. The automatic decoupling mechanism has roller assembly with lower driving sleeve, installation sleeve assembly with support sleeve, lever poking assembly with upper driving sleeve, hook lifting rod inside the coupler, locating chain inserted inside the locating sleeve to limit the portion of the automatic decoupling mechanism and realize the coupling between the mechanism and the coupler, and ramp device installed on the ground the railway freight car pass through. During decoupling operation, the coupler ring is lifted automatically while the roller assembly is made to move upwards by the hump so as to decouple. |