With the deepening of human society's understanding and exploration of the ocean, higher requirements for un- derwater monitoring and detection equipment are put forward. Detection array model and array signal processing algorithm determine the complexity of monitoring and detection equipment. Aiming at the complex environment of specific underwater multi-target posi- tioning platform, this paper establishes an arbitrary spatial array mathematical model, introduces the fourth-order cumulant algo- rithm, and analyzes the array expansion characteristics of the fourth-order cumulant, the theoretical basis of DOA estimation for multi-target with less degrees of freedom in arbitrary array shape is established. Computer simulation results show that the algorithm is correct and effective.
