In order to control the disturbance from momentum wheels of a satellite, a new type vibration isolator, using elastic planar cable net, was proposed to set momentum wheel components and satellite bearing cylinder apart, as to minimize the disturbance. Thus the working environment of the sensitive payloads is ensured, with less disturbance energy transmitted to the bearing cylinder. Experiments were conducted to verify the vibration isolation function of the cable net and test the influence of substructures on its isolation performance. While analyzing the cable net, the nonlinear property was found in such a structure. Then an equivalent nonlinear SDOF model was used to investigate the nonlinear dynamic response of the cable net, which is subject to harmonic excitation. On the other hand, the influence of cable net parameters on dynamic response of the structure is analyzed, through varying density of the net grid and pretension forces. Such an analysis will make the design of cable net isolator and parameter optimization more convenient.