To overcome the problem that the vibration isolation performance between the resonance region and the vibration isolation effective region can not be balanced by the passive vibration isolation technique, the active nonlinear damping control strategy with the inherent time delay is proposed. Firstly, the multi-scale perturbation method is applied to investigate the primary resonance for the examined time-delay active damping isolation system, which possesses the piecewise bilinear stiffness. Then the concepts of equivalent stiffness and damping are established, and effects of the time delay on the amplitude frequency characteristics of the controlled system are investigated. As a result, it can be seen that by choosing the proper feedback gain, the saddle-node bifurcation can be effectively suppressed, and the occurrence of jumping phenomenon can be avoided as well. At last, according to the response stability analysis, the parameter intervals for feedback gain and beneficial time delay are given.