In consideration of the influence of infection timedelay on the transmission of zero-day virus, the time-delay transmission model of zero-day virus and its stability under the background of platform dynamic defense are studied, the following measures should be taken in the research. Firstly, the influence of time-delay on the propagation of zero-day virus is analyzed, and the Dynamic Platform Defense model is introduced, and a SIZRO model of zero-day virus propagation is established. Secondly, according to the Lyapunov stability criterion, the local stability of equilibrium point in system is proved, and the basic reproduction number and its effect on the zero-day virus transmission are analyzed. Finally, the number of infected nodes in SIZDR model being compared with that in SIZRO model, the feasibility of using platform dynamic defense to solve zero-day virus transmission problem is demonstrated. The theoretical analysis and simulation results show that the proposed model can objectively reflect the time-delay propagation and immune law of zero-day virus, and the Dynamic Platform Defense can effectively improve the defense effect of the system against zero-day virus.