The utility model relates to a 750kV icing flashover preventing composite insulator chain. The composite insulator chain comprises a big umbrella skirt and a cleaning device. The composite insulator chain is characterized in that the big umbrella skirt comprises a big umbrella skirt I (6a) and a big umbrella skirt II (6b); the cleaning device comprises cleaning sheets (2), blades (3), a brush head (4) and a fixed ring (5); the cleaning sheets (2) are in a ??C?? shape; the brush head (4) is fixed on the ??C??-shaped inner sides of the cleaning sheets (2); the outer edge shape of the brush head (4) is matched with the appearance of an umbrella disc (1) of a sub umbrella of the insulator chain; and the blades are fixedly arranged in the middles of the ??C??-shaped outer sides of a part of all the cleaning sheets (2). The 750kV icing flashover preventing composite insulator chain has the advantages of reasonable structure and reliable performance, and can effectively improve the alternating-current flashover voltage of a pollution icing composite insulator. Therefore, the composite insulator chain has great social and economic benefits.