The torsion behavior of composite submarine cables often occurs due to external load during the laying and operation. A 3 dimension numerical simulation model of composite submarine cable is established using the finite element software. The clockwise-anticlockwise torsion characteristics of the steel armor, copper conductor and optical fiber of cables are mainly studied. The results show that the stress of each structure along the twisted direction of the steel armor, copper conductor and optical fiber is greater than that in the opposite direction, which leads to a wide range of stress concentration in the copper conductor. The torsion angle of the internal structure of the marine cable along the axial direction has a good consistency and shows linear variation characteristics. In the case of small angle torsion, the stress of each structure increases first and then decreases. When the torsion angle increases, the stress of each structure increases gradually, and the growth rate increases. The materials successively yield during the torsion.