Webs are used to capture prey, therefore the structure and mechanical properties of the webs can affect the efficiency of prey capture and foraging investment. Is there an Effect of the prey experience on tensile behavior and properties of silk fiber? In this paper, tensile properties of forward and returning preying dragline silk, when A. bruennichi preyed on T. molitor and the effects of the predator experience on tensile properties of radius silk before and after mending were examined and investigated using electric single-fiber tensile apparatus. The data dealt with Spass 17.0. Figure 1 and table 1 show that compared with forward preying dragline silk (Du=12.2±2.5 mm, Fu=5.12±0.53 cN), return preying dragline silk reduces investment in the elastic region and increases investment in the yield and hardening region(Du=23.94±0.50 mm, Fu=8.07±3.70 cN, PD=0.001＜0.01, PF=0.242＞0.05), moreover returning preying dragline silk present higher toughness. Figure 2 and table 2 show that compared with initial radius silk (Du=7.18 mm, Fu=0.51 cN), radius mending silk under no feeding T. molitor increases investment of tensile properties (Du=9.73±0.94 mm, Fu=3.37±0.85 cN). However, radius mending silk under feeding T. molitor reduces investment of tensile properties (control silk：Du=21.93 mm, Fu=9.877cN, mending silk：Du=18.47±3.43 mm, Fu=3.01±1.4 cN). In addition, Figure 1 and 2 also demonstrated that two types of tensile behaviors present in tested samples of spider silk: one is the typical of tensile behavior similar with dragline silk; the other one is the tensile behavior of material of the viscous flow, which reflects the tensile properties, is the strategy of another kind of materials. It can content with the demand that spider silk dissipate absorb kinetic energy of prey and spider itself when it fall down. This study shows that spider can adjust mechanical properties of spider silk according its prey experience following cost-benefit principles in order to adjust prey inputs.