Abstract: To reveal the interaction process and mechanism of spherical fragment penetrating a gelatin target with soft fiber protection, the penetration process of spherical fragment to the ballistic gelatin target with soft fiber protection was simulated using an FAE method, and the feasibility of the simulation method was verified via experiment. The result shows that the velocity of gelatin sinking rises rapidly, while the velocity of steel sphere slows down quickly as the steel sphere impacts the soft fiber protection. Meanwhile the main failure mode of soft fiber is shearing mode. With the decrease of the velocity of steel sphere, the tensile deformation of soft fiber becomes more obvious, kinetic energy of steel sphere is converted to potential energy of fiber shells and the failure mode turns into tensile mode. Although the soft armor doesn't break, the back of fiber becomes protruding. With spreading of pressure wave, the gelatin depresses slightly,and the peak pressure is up to 3.53 MPa at 40 mm inside the gelatin, which still can cause certain damage to human organs.