Accompanying escort antisubmarine with shipborne antisubmarine helicopter is an important method to ensure the security of surface ship formation.A new method of triangle search method was proposed according to the actual needs of flanking escort antisubmarine and the characteristics of antisubmarine helicopter when searching submarines with dipping sonar.The synchronization model was established and the synchronization between patrol searching line and the formation was realized effectively.The searching effectiveness of the triangle search method was simulated by using the simulation models established.The specific operational application of the model was optimized with the simulation result.This method can offer a theoretic foundation for the helicopter flanking escort antisubmarine operating application.