Abstract: Pre-stressed single-layer cable net falls into the group of flexible tensile structures with its strong geometric nonlinearity, which provides the cable net with the stiffness out of plane as a result of stress stiffing together with pre-stress. Due to the limited stiffness offered by the pre-stress of cable, the cable net will undergo large deflection under certain loads, which make it necessary to take into the account of the large deflection effects, which triggers the strong geometrical nonlinearity. Considering the importance of nonlinearity of the mechanical characteristics of cable net, this paper quantified the nonlinearity of cable net with a factor of nonlinearity; with the help of transient analysis of cable net of different geometric nonlinearity, the seismic response was investigated under harmonic activation. Finally, we concluded that the shape of cable net and the pre-stress affect the nonlinearity greatly; peak resonant vibration would move aside for its nonlinearity and its corresponding frequency is rather different from the linear frequency and nonlinear frequency provided by other scholars.