The invention discloses a flexibly connected double unmanned ship autonomous collaboration method for rounding up oil spillage. The method comprises the steps of (1) planning a sailing trajectory capable of meeting multiple constraint conditions according to the oil spillage position, the initial positions of unmanned ships and dynamic characteristics of the flexibly connected unmanned ships; (2) performing trajectory tracking on the acquired sailing trajectory; (3) correcting the expected heading and speed of each unmanned ship in real time according to influences of a flexible connection acting force and force moment by adopting a fuzzy null space based behavior fusion method in order to ensure the unmanned ships to fulfill the task and reduce adverse influences of the flexible connection acting force and force moment in the process of performing trajectory tracking; and (4) calculating a control instruction by a motion controller of the unmanned ships so as to drive the actual heading and speed of the unmanned ships to reach the expected values. According to the invention, adverse influences generated by the flexible connection acting force and force moment are effectively eliminated by using the fuzzy null space method, and autonomous collaboration control for the flexibly connected double unmanned ship is realized.