Considering the harmfulness of driving environment and the vibration frequency of vehicle-borne precision instruments, a quasi-zero-stiffness(QZS) vehicle vibration isolation system with small space proportion and convenient installation was designed and manufactured.A vertical spring was connected in parallel with two symmetrical negative stiffness structures which were used for stiffness calibration.Based on a static analysis, the parameter conditions for the system with QZS in equilibrium position were preliminarily determined.In the derivation, a machining error coefficient was introduced, and its influence on the QZS of the system was analyzed.The nonlinear dynamic equation of the system was established and the average method was used to get the dynamic response of the system under harmonic displacement excitations of the vehicle body.The influences of the system parameters and the excitation amplitude on the displacement transfer rate were analysed.On this basis, a QZS vibration isolation system was designed and manufactured, and tests were carried out under different excitation amplitude and frequency.The measured amplitude frequency response curve of the displacement transfer rate was compared with the theoretical calculation results.In addition, a co-simulation by Trucksim/Simulink was carried out under vehicle random excitation condition.The research shows that the experimental results are in good agreement with the theoretical results, which verifies the correctness of the theoretical modeling and analysis method for the QZS vibration isolation system.The initial vibration isolation frequency of QZS is about 1.4 Hz, which is better than that of a corresponding linear system by 2.9 Hz.The RMS value of displacement response of the vehicle body with the vibration isolation unit is reduced by more than 80%, and the acceleration is reduced by about 90%.The stability of the quasi-zero stiffness vibration isolation system in steady state is rather good, which shows it has good vibration isolation performance.