The invention provides a flexible connecting device. The flexible connecting device comprises a supporting beam, a metal hose and multiple elastic stay ropes; the two ends of the supporting beam are in sliding connection with tops of two to-be-connected pipelines through pipefitting connection accessories; the two ends of the metal hose are connected with ports of the two to-be-connected pipelines, one end of each elastic stay rope in the multiple elastic stay ropes is fixed to the supporting beam, and the other ends of the stay ropes are fixed to the metal hose. Through the application of thedevice, the problems that in the prior art, the metal hose occupies large space, the application is limited, medium flow resistance is large, and the cost is high are solved.