Despite its advantage of improving the spectrum and hardware efficiency, integrated sensing and communication (ISAC) system is susceptible to eavesdropping due to the open nature of wireless channels. In this paper, we investigate the secure transmission of ISAC aided by an intelligent reflecting surface (IRS) and unmanned aerial vehicle (UAV). Moreover, assuming that an aerial target is a potential eavesdropper, the artificial noise is introduced to disrupt the eavesdropping, while enhancing the sensing signal-to-noise ratio and the users’ quality of service. Aiming to maximize the sum secrecy rate, we jointly optimize the UAV deployment, BS transmit beamforming, artificial noise power and passive beamforming. The formulated non-convex problem is decomposed into three subproblems and solved via an iterative alternating optimization algorithm. Specifically, we introduce auxiliary variables to transform the non-convex subproblems into convex ones. For the UAV deployment solution, it can be obtained by successive convex approximation. With the optimal UAV deployment, the BS transmit beamforming, artificial noise power and passive beamforming can be derived by semi-definite relaxation. Finally, we present simulation results to validate the performance improvement of the proposed scheme on the security of ISAC.