The motion prediction method of the wave glider with flexible connection, the specific steps are as follows: (1) Obtain the rudder angle information (2) Calculate the force on the submerged body (3) Calculate the flexible chain pull force on the submerged body; (4) Judge the submerged body If the direction of the vertical flexible chain pulling force is vertically upward, then return to (2), if it is vertically downward or zero, then store the current moment state information as (5) initial state, enter (5); (6 ) to calculate the distance between the floating body and the submerged body, if the distance is less than the length of the flexible chain, then return to (5); if the distance is greater than the length of the flexible chain, then store the current state information as the initial state of (1), and return to (1); if the distance is equal to length of the flexible chain, then enter (7); (7) judge the relative movement trend of the floating body and the submerged body, if they are close to each other or relatively static in the direction of the connection between the two, then return to (5); if they are far away from each other, then store the current Time state information is used as 1) initial state, and returns (1).