Aiming at the disadvantages of narrow frequency band, low sensitivity, and ambiguity between the port hand and the starboard existing in microelectromechanical system （MEMS） bionic vector hydrophone, a composite MEMS hydrophone was designed in this paper. An array consisting of 4 bionic vector hydrophone with different length of cilia was selected as the vector part, of which the parallel method between the structures was used. The operating frequency was extended to 4 800 Hz, and 4 different frequency bands were segmented, while broadened the frequency bandwidth and the sensitivity was ensured at the same time. The scalar part used the low frequency capacitance hydrophone sensor for the design optimization. The cavity was filled with silicone oil and the acoustic holes were opened in the diaphragm, while the pressure capacity of the diaphragm was enhanced and good dynamic performance was ensured at the same time. The scalar and vector information was processed through a joint algorithm of acoustic energy flux, thus the ambiguity between the port hand and the starboard was effectively eliminated. The working principle of composite MEMS hydrophone was introduced in this paper and the simulation verification was carried out through the ANSYS workbench. The cavity and bottom electrode were defined in glass and the fourarm and diaphragm were defined on SOI. The proposed hydrophone has good whole structure consistency and high positioning accuracy.