A derailleur drive chain structure for downhill event operating in conjunction with a gear disk includes inner chain plates, outer chain plates, sleeves, and pins. Each sleeve is disposed between each pair of inner chain plates. Each pin is to connect each pair of abutted outer and inner chain plates. Two ends are provided on a first side of each outer chain plate. The outer edge of each outer chain plate externally to the two ends is disposed with a protruding portion to improve tensile strength and flexibility of the chain to upgrade its impact withstanding performance for improving riding safety.