According to the underwater collaborative ball-scrambling project in the global vision group of the International Under-Water Robot Competition, we pose an effective multi-robot ball-scrambling strategy. In terms of the four aspects of speed control, direction control, multi-fish cooperation and heading action, the overall strategy is formulated to design the special position. The robotic fish alternates the topping ball has been tested repeatedly. The application in the case illustrates that the overall strategy has increased the robot fish efficiency in the ball scrambling competition and completed the game task more effectively. In addition, it has won the championship in the 2018 International Water Robot Competition.