To achieve favorable hole-opening performance against underwater armored protection and effective penetration in water medium simultaneously with a single shaped charge structure， and to overcome the single-functionality limitation of conventional underwater shaped charges， a finite element model was established based on the W shaped charge structure. The reliability of the simulation results was validated by comparison with jet formation and penetration experiments from the literature. The underwater formation mechanism and penetration performance of the multimode damage elements were further investigated. The results show that by controlling the initiation mode， the W shaped charge can form two types of damage elements： an explosively formed projectile （EFP） and an annular jet. The penetration depth of the EFP into water medium is proportional to the inner liner thickness （value a）， while the penetration hole diameter of the annular jet in the target plate is inversely proportional to value a. When value a increases from 3.2 mm to 7.2 mm， the penetration depth of the EFP in water medium increases by 239.2%， and the penetration hole diameter of the annular jet decreases by 30%. The penetration depth of the EFP into water medium is inversely proportional to the outer liner thickness （value b）， while the penetration hole diameter of the annular jet in the target plate is proportional to value b. When value b increases from 1.5 mm to 2.5 mm， the penetration depth of the EFP in water medium decreases by 63.5%， and the penetration hole diameter of the annular jet increases by 45.4%. This study can provide references for the design of underwater shaped charges and multimode shaped charges.